XII. THE ORDER INSECTIVORA
The Insectivora comprise a number of comparatively small mammals, generally of terrestrial, although rarely of arboreal or aquatic habits, and presenting the following common features. They are unguiculate, and have plantigrade or subplantigrade, and generally pentadactylate feet, in which the pollex and hallux are not opposable to the other digits. They are diphyodont and heterodont, and the teeth are rooted. The molars are studded with sharp cusps, the crowns of the upper molars being either quadrangular or triangular; there are never less than two incisors in either side of the mandible; and in many cases the incisors, canines, and anterior premolars are not clearly differentiated from one another (Fig. 280); the canines being usually weak. Clavicles are present, except in Potamogale. The body is clothed with fur or protected by an armature of spines; the testes are inguinal or placed near the kidneys, and are not received into a scrotum; the penis is pendent or suspended from the wall of the abdomen; the uterus is two-horned and with or without a distinct corpus uteri; the placenta is discoidal and deciduate; and the smooth cerebral hemispheres do not extend backwards over the cerebellum (Fig. 281). The projection of the muzzle far beyond the extremity of the lower jaw is a very general feature. The humerus generally has an entepicondylar foramen. Certain forms, such as Talpa and Galeopithecus, are unique among mammals in having ossified intercentra in the dorso-lumbar region of the vertebral column.
Representatives of this order are found throughout the temperate and tropical parts of both hemispheres (except South America and Australia), and exhibit much variety both in organisation and in habits. With the exception of the Tupaiidæ, all are nocturnal; the greater number are cursorial, but some (Talpa, Chrysochloris, Oryzorictes) are fossorial; some (Potamogale, Nectogale, Myogale) are natatorial, and a few (Tupaiidæ) arboreal; while the species of the aberrant genus Galeopithecus glide through the air like the Flying Squirrels. To the great majority the term insectivorous is strictly applicable, Galeopithecus alone being phytophagous; while Potamogale is said to feed on fish, and the different species of Moles live chiefly on worms. The general organisation of the Insectivora indicates a very low type, and were it not for the specialised character of their placentation and the tendency to lose the differentiated characters of the anterior teeth they might be regarded as closely allied to the ancestral type of many of the heterodont mammals. The strongly marked distinction of the canines from the incisors and anterior premolars in the Mesozoic and most of the Tertiary mammals (excepting some of the Ungulates) points, however, very decidedly to the conclusion that the want of definition between these teeth in many of the modern Insectivora is an acquired feature. Fossil forms apparently indicate a relationship on the one hand with the Creodont Carnivora, and on the other with the Lemuroid Primates; indeed it is in some instances impossible to say whether extinct genera are really Insectivores or Lemuroids.
In most Insectivora the cranial cavity is of small relative size, and in none is the brain-case elevated to any considerable extent above the facial line. The facial part of the skull is generally much produced, and the premaxillary and nasal bones are well developed. The zygomatic arch is usually slender or deficient, the latter being the case in most of the species; and postorbital processes of the frontals are found only in the Galeopithecidæ, Tupaiidæ, and Macroscelididæ. The number of dorsal vertebræ varies from 13 in Talpa to 19 in Centetes; that of the lumbar from 3 in Chrysochloris to 6 in Talpa and Sorex; and of the caudal from the rudimentary series of 8 in Centetes to the 40 or more of Microgale. Not less variable are the characters of the vertebræ themselves; the spinous processes often being very long in one and short in another species of the same genus. In the Soricidæ and Myogale the neural arches of the cervical vertebræ are very slender. In the Soricidæ and Gymnura the four anterior vertebræ develop large single hypapophyses. In Galeopithecus the centrum of each vertebra supports posteriorly a pair of intercentral ossifications; while in Erinaceus, Myogale, and Talpa small oval ossicles are found on the inferior surfaces of the lumbar interspaces. In Erinaceus, owing to the thickness of the neural cord in the cervical region and its abrupt termination, the diameter of the neural canal in the cervical and first two dorsal vertebræ greatly exceeds that of any of the succeeding vertebræ. The sternum is variable, but generally narrow, bilobate in front, and divided into segments. The pectoral girdle presents some remarkable adaptive modifications, most fully expressed in Talpa, having relation to the use of the fore limbs in burrowing; but in the Golden Moles (Chrysochloris) the forearm and manus alone become specially modified for this purpose. In Galeopithecus and Macroscelides the bones of the forearm (radius and ulna) are distally united. The manus has generally five digits, but in Rhynchocyon and in one species of Oryzorictes the pollex is wanting, while in the true Moles it is extremely modified. The femur has, in most species, a prominent ridge below the greater trochanter representing a third trochanter. In Galeopithecus, Tupaia, Centetes, Hemicentetes, Ericulus, and Solenodon the tibia and fibula are distinct, but in all the other genera more or less united together. The pes usually possesses five digits (rarely four by reduction of the hallux); and in some forms, as in the leaping species (Macroscelides, Rhynchocyon), the tarsal bones are greatly elongated. The form of the pelvis, and especially of the symphysis pubis, varies within certain limits; and these differences have been proposed by Leche as a basis for the classification of the families. Thus in the Galeopithecidæ, Tupaiidæ, and Macroscelididæ there is a long symphysis; in the Erinaceidæ, Centetidæ, and Potamogalidæ the symphysis is short; and in the Soricidæ, Talpidæ, and Chrysochloridæ there is none.
Space does not admit of attempting a sketch of the modifications of the muscular system, which will be found fully described in Dr. Dobson’s Monograph, referred to in the bibliography. As to the nervous system, it has been already mentioned that the brain throughout the order presents a low type of organisation; in none of the members do the cerebral hemispheres present any trace of convolutions, nor do they extend backwards so as to cover the cerebellum, while the olfactory lobes are large and project in front, and the corpus callosum is short and thin. In the Hedgehogs (Erinaceus) the spinal column ends abruptly opposite the third or fourth dorsal vertebra in a slender filament, and the dorsal and lumbar nerves, given off in front of this point, are carried backwards in two compressed bundles occupying the suddenly narrowed spinal canal as far as the sacrum.
Owing to the similarity in the character of the food, the truly insectivorous species, forming more than nine-tenths of the order, present little variety in the structure of their digestive organs. Except in Galeopithecus the stomach is a simple, thin-walled sac; but in some, as in Centetes and allied genera, the pyloric and œsophageal openings are very close together. The intestinal canal has much the same calibre throughout, and varies from three (in the Shrews) to twelve times (in the Hedgehogs) the length of the head and body. In the arboreal genera, Galeopithecus and Tupaia, as well as in the Macroscelididæ, all of which probably feed in part on vegetable substances, most of the species possess a cæcum. The liver is deeply divided into lobes, the right and left lateral being cut off by deep fissures; and both the caudate and Spigelian lobes being generally well developed. The gall-bladder, which is usually large and globular, is placed on the middle of the posterior surface of the right central lobe.
In most of the members of the order (Soricidæ, Centetidæ, Chrysochloridæ) the penis is capable of being more or less completely retracted within the fold of integument surrounding the anus; in some (Galeopithecidæ, Talpidæ) it is pendent in front of the anus; while in others (Macroscelididæ, Erinaceidæ, Solenodontidæ) it is carried forwards and suspended from the abdominal wall. In the subfamily Centetinæ and Chrysochloris the testes lie immediately behind the kidneys, but in others more or less within the pelvis. During the rutting season they become greatly enlarged, forming protrusions in the inguinal region. Except in Rhynchocyon the uterine cornua are long and open into a short corpus uteri, which in many species (Soricidæ, Talpidæ, Centetidæ, Chrysochloridæ) is not separated from the vagina by a distinct os uteri. With the exception of Galeopithecus all Insectivora appear to be multiparous, the number of young at a birth varying from two to eight in Erinaceus, and from twelve to twenty in Centetes. The position of the mammary glands and the number of the teats vary greatly. Thus in Galeopithecus there are two pairs of axillary teats, and in Solenodon a single post-inguinal pair; but in most species they range from the thorax to the abdomen, varying from two pairs in Gymnura to twelve in Centetes. In Chrysochloris the thoracic and inguinal teats are lodged in deep cup-shaped depressions.
Odoriferous glands exist in many species. In most Shrews these glands occur on the sides of the body at a short distance behind the axilla, and their exudation is probably protective, since few carnivorous animals will eat the dead bodies of these creatures. In both species of Gymnura and in Potamogale large pouches are situated on either side of the rectum and discharge their secretions by ducts, opening in the first-named genus in front of, and in the latter within the margin of the anus. In Centetes the ducts of similarly situated racemose glands open by pores at the bottom of deep pits placed at either side of the anus.
The integument is thin, but in many species is lined by a muscular coat, which is probably more developed in the Hedgehogs (Erinaceidæ) than in any other mammal. In this family and the Centetidæ most of the species are protected by spines implanted in the panniculus carnosus muscle, and more or less replacing the fur of the upper surface of the body.
The order is usually divided into two suborders, but the very aberrant genus which constitutes the first might well be raised to ordinal rank. It has little in common with the true Insectivora, but as it certainly belongs to no other of the recognised mammalian orders it is retained among them chiefly to avoid the inconvenience of increasing the number of ordinal divisions for the sake of a single isolated form.
Suborder DERMOPTERA.
Upper and lower incisors compressed, multicuspidate, the lower deeply pectinated; fore and hind limbs connected by a broad integumentary expansion forming a parachute.
Family GALEOPITHECIDÆ.
In addition to the characters given under the head of the suborder it may be mentioned that the orbit is nearly surrounded by bone, the zygomatic arches are well developed, the tympanic forms a bulla, the ulna is distally united with the radius, the tibia and fibula are distinct, the pubic symphysis is long, the penis is pendent, the testes are received into inguinal pouches, the mammæ are axillary, the uterus is two-horned, and there is a large cæcum.
Galeopithecus.[530]—Dentition: i ²⁄₃, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 34. Second upper incisor and canine with two roots. Two species—G. volans and G. philippinensis. The former, which is distinguished from the latter by the form of the upper incisors, has a total length of nearly 2 feet. The long and slender limbs are connected by a broad integumentary expansion extending outwards from the sides of the neck and body, and forming also a web between the fingers and toes as far as the base of the claws (Fig. 282); the hind limbs are further connected by a similar expansion passing outwards along the back of the feet to the base of the claws, and, inwardly, involving the long tail to the tip, forming a true interfemoral membrane, as in the Bats.
The two species of Flying Lemurs, as the representatives of this genus are commonly but erroneously called, live in the forests of the Malay Peninsula, Sumatra, Borneo, and the Philippine Islands, where they feed chiefly on the leaves and fruits of trees. Their habits are nocturnal, and during the daytime they cling to the trunks or limbs of trees, head downwards, in a state of repose. With the approach of night their season of activity commences, when they may be seen gliding from tree to tree supported on their cutaneous parachute, and they have been observed to traverse in this way a space of 70 yards with a descent of only about one in five.
Galeopithecus was referred by some of the older zoologists and anatomists to the Bats, and by others to the Lemurs, but Professor Peters’s view, that it belongs to neither of these orders, and should be considered an aberrant Insectivore, has been very generally accepted, although, as mentioned above, the association is by no means a close one. Besides differing from the Bats in the form of the anterior limbs and of the double-rooted outer incisor and canine, it also contrasts strongly with them in the presence of a large sacculated cæcum, and in the great length of the colon, which is so remarkably short in all the Chiroptera. From the Lemurs, on the other hand, the form of the brain, the characters of the teeth, the structure of the skull, and the deciduate discoidal placenta completely separate it. In a recent elaborate memoir on the myology and affinities of Galeopithecus Dr. Leche[531] considers that we have in this genus an indication of the mode in which the Insectivora were modified into the Chiroptera, although it is completely off the direct line of descent. The deeply pectinated crowns of the lower incisors of Galeopithecus are quite unique in the class, and the only approach to the double-rooted canine, except in Erinaceus and Talpa, is found among the Marsupials in Perameles, where the root of the canine is grooved.
Suborder INSECTIVORA VERA.
Upper and lower incisors conical, unicuspidate or with basal cusps only, the lower not pectinated; limbs free, formed for terrestrial progression.
The following table gives a key to the distinctive characters of the existing families:—
I. Upper molars broad, multicuspidate, with more or less well-defined W-shaped crowns.
A. Symphysis pubis long; generally a cæcum; cerebral cavity comparatively large.
a. Orbit encircled by bone; metatarsus moderate; arboreal. Tupaiidæ.
b. Orbit not encircled by bone; metatarsus greatly elongated; terrestrial. Macroscelididæ.
B. Symphysis pubis short or none; no cæcum; cerebral cavity small; skull without postorbital processes.
a. First and second upper molars with a central fifth cusp.
a′. Tympanic annular, not forming a bulla. Erinaceidæ.
b. No central fifth cusp to upper molars.
a′. Tympanic annular, not forming a bulla; no zygomatic arch. Soricidæ.
b′. Tympanic forming a bulla; zygomatic arch developed. Talpidæ.
II. Upper molars narrow, with V-shaped crowns.
a′. Tympanic annular, not forming a bulla; zygomatic arch imperfect.
a″. No clavicles. Potamogalidæ.
b″. Clavicles well developed.
a‴. Skull constricted between the orbits; penis suspended. Solenodontidæ.
b‴. Skull not constricted; penis pendent, retractile. Centetidæ.
b′. Tympanic forming a bulla; zygomatic arch well developed. Chrysochloridæ.
The second section, in which the molars are of the primitive tritubercular type, should probably be regarded as containing the most generalised representatives of the order; and it is noteworthy that the whole of them are confined to Africa, Madagascar, and the West Indies, whereas most of the first section are widely distributed over the Palæarctic and Oriental regions. None of the existing families of the second section are known in a fossil condition, although it is suggested that the extinct Leptictidæ includes allied types.
Family TUPAIIDÆ.
Skull with comparatively large brain-case, orbit surrounded by bone, well-developed zygomatic arch, perforated jugal, and a tympanic bulla. Upper molar broad, with cusps arranged in a W. Pubic symphysis long; radius and ulna, and tibia and fibula separate; metatarsus only slightly longer than tarsus. Usually a short cæcum. Habits arboreal and diurnal. Confined to the Oriental region.
Tupaia.[532]—Dentition: i ²⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 38. Feet naked beneath, the sole furnished with projecting pads; claws moderate, curved, and sharp; head pointed; ears rounded; tail bushy, distichous, with short hair below. The Tree-Shrews, of which there are some nine species, are found in India, Burma, the Malay Peninsula, the Nicobars, Sumatra, Java, and Borneo. The species closely resemble one another, differing chiefly in size and in the colour and length of the fur. Their general appearance is very Squirrel-like. Their food consists of insects and fruit, which they usually seek in the trees, but also occasionally on the ground. When feeding they often sit on their haunches, holding the food, after the manner of Squirrels, between their forepaws.
Ptilocercus.[533]—Represented only by the Pentailed Tree-Shrew (P. lowi, Fig. 283) of Borneo, in which the tail is of extraordinary length, with the proximal two-thirds naked, and the remaining third furnished with a bilateral fringe of long hairs, from which the genus takes its name.
Extinct Genera.—An Insectivore from the Middle Miocene of France, described as Lantanotherium, is said to be nearly allied to Tupaia. The genus Parasorex, from strata of similar age, has the dental formula i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃, and is regarded as connecting the present with the following family.
Family MACROSCELIDIDÆ.
Skull with comparatively large brain-case, strong zygomatic arch, a tympanic bulla, orbit surrounded by bone, imperforate jugal, and usually no postorbital process. Molars broad, with four cusps arranged in a W. Pubic symphysis long; proximal end of tibia and fibula united; radius and ulna united or separate; metatarsus much longer than tarsus. A large cæcum. Habits terrestrial, saltatorial, and nocturnal. The family is confined to Africa.
Macroscelides.[534]—Dentition: i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ²⁄₂₋₃; total 40 or 42. Distal extremity of radius and ulna united. Five digits in manus, and five or four in pes. This genus, which is taken to include Petrodromus, comprises ten species widely distributed throughout the African continent. All are closely related, resembling one another in general form, and even in the colour of the fur. They fall into two groups, distinguished by the presence or absence of a small third lower molar.[535] M. tetradactylus (Fig. 284), the type of the genus Petrodromus, differs from all the other species in the absence of the hallux, and of the third lower molar. These animals are commonly known as Jumping Shrews, and, like the following genus, have the muzzle much produced.
Rhynchocyon.[536]—Dentition: i ¹⁄₃, c ¹⁄₁, p ⁴⁄₄, m ²⁄₂; total 36. Upper incisor frequently shed in the adult. Radius and ulna distinct; hind limbs relatively shorter, and proboscis longer than in the type genus; four digits in each foot. Four closely allied species have been described from East Africa. The head and body of the type species measures about 8 inches in length; and the long tail is covered with a ringed skin, sparsely haired. Its habits are fossorial.
Family ERINACEIDÆ.
Skull with a small brain-case; no postorbital process; slender and occasionally imperfect zygomatic arch, and an annular tympanic, which does not form a bulla. Upper molars with four principal cusps and a small central median cusp. Acromion of scapula bifid; pubic symphysis short; radius and ulna free, but tibia and fibula united proximally. No cæcum; penis carried forward and suspended from the wall of the abdomen. Habits terrestrial. Found in the Palæarctic, Ethiopian, and Oriental regions.
Subfamily =Gymnurinæ=.—Palate completely ossified; pelvis very narrow; fur without spines.
Gymnura.[537]—Dentition: i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 44. This genus, if Hylomys is rightly included, is represented by the two species, G. rafflesi and G. suilla, from the Malay Peninsula and Indian Archipelago. The former has the appearance of a large Rat with a long tail and head and projecting mobile snout; the latter, which is much smaller, with a short tail and small third upper premolar, has long been known under the name of Hylomys suillus, and classed with the Tupaiidæ. Both species present a very generalised type of dentition, in this respect occupying an almost central position in the order. G. suilla is represented in Mount Kina-Balu, Borneo, by a variety characterised by the presence of a dark dorsal streak. Many zoologists prefer to retain Hylomys as a distinct genus.
Subfamily =Erinaceinæ=.—Palate imperfectly ossified; pelvis wide; fur with spines.
Erinaceus.[538]—Dentition: i ³⁄₂, c ¹⁄₁, p ³⁄₂, m ³⁄₃; total 36. The first pair of upper incisors (Fig. 285) are considerably larger than the others, and are widely separated from one another in the middle line; the canine is very similar to the third incisor; and, except in E. europæus (Fig. 285), each of these teeth is inserted by two distinct roots (Fig. 280, p. 610). The first lower incisor is large and proclivous. The number of vertebræ is C 7, D 15, L 6, S 3, C 11.
The Hedgehogs comprise nearly twenty species, distributed throughout Europe, Africa, and the greater part of Asia, but not found in Madagascar, Ceylon, Burma, Siam, the Malay Peninsula, or Australia. All the species resemble one another in the armature of spines investing the upper surface and sides of the body; and all possess the power of rolling themselves up into the form of a ball, protected on all sides by the strong spines; the dorsal integument being brought downwards and inwards over the head and tail, so as to include the limbs also, by the action of special muscles. The common Hedgehog (E. europæus) is the most aberrant species, differing from all the rest in the peculiarly shaped and single-rooted third upper incisor and canine (Fig. 285), and in its very coarse, harsh fur. The dentition of the long-eared North Indian form, E. collaris (Fig. 280), may be considered characteristic of all the other species, the only important differences being found in the variable size and position of the second upper premolar, which is very small, external, and deciduous in the Indian E. micropus and pictus. The former species, limited to South India, is further distinguished by the absence of the jugal bone. Of the African species, E. diadematus, with long frontal spines, is probably the commonest; while E. albiventris has been made the type of a separate genus on account of the total absence of the hallux.
The well-known European species feeds on insects, worms, slugs, mice, rats, lizards, snakes, etc., as well as on eggs, fruit, and roots. It hibernates during the winter. The young are usually produced in July or August in litters of not more than four, but there may be a second litter in October; and the period of gestation is believed not to exceed a month. The Indian, and probably also the African species, do not hibernate.
The existing E. europæus dates from the Pleistocene period, and extinct species of the genus are found in the Upper and Middle Miocene of the Continent.
Extinct Genera.—The French Lower Miocene genus, Palæoerinaceus, appears to be allied to Erinaceus, but is distinguished by the wider and completely ossified palate. In the Upper Eocene of Central France there are two genera, which appear to be most nearly allied to Gymnura, although connected by Palæoerinaceus with Erinaceus. Of these Necrogymnurus,[539] with which Cayluxotherium is apparently identical, has teeth like Gymnura, but an imperfectly ossified palate like Erinaceus; and the skull is remarkable for the peculiar rugose structure of the parietal and temporal regions. Comphotherium is distinguished by the presence of a cingulum to the lower molars, like that found in Gymnura.
Family SORICIDÆ.
Skull (Fig. 286) long and narrow, with no zygomatic arch or postorbital process, and the tympanic ring-like and not forming a bulla. Upper molars with the cusps arranged in a distinct W. No pubic symphysis. The tibia and fibula united. No cæcum. Habits usually terrestrial, rarely aquatic. Distribution extensive.
The Shrews are Rat-like or Mouse-like insectivores, with the body covered with hair, and the muzzle long and pointed. Their dentition (Fig. 286) is peculiar and characteristic. Thus the first upper incisor is large and hook-like, with a more or less developed basal cusp on the posterior border. Between this and the last premolar there are a variable number of small teeth, representing the other incisors, the canine, and the anterior premolars; although, owing to the early obliteration of the maxillo-premaxillary suture, their homology is exceedingly difficult to determine. Three molars are invariably present, of which the third is much the smallest. In the mandible there are always six teeth, but in one species of Myosorex there may be a seventh. The first lower incisor is usually directed horizontally forwards; the second incisor (formerly reckoned as the canine) is the smallest tooth of the series, the fourth premolar being slightly larger.
This family, which includes considerably more than half the representatives of the order, has a distribution coextensive with the latter. Many classifications of this difficult group have been attempted, but according to the latest proposal of Dr. Dobson,[540] the genera may be divided into two subfamilies, distinguished by the apparently trivial character of the colour of the teeth.
Subfamily =Soricinæ=.—Summits of the teeth coloured red.
Sorex.[541]—Dentition: i ⁴⁄₂, c ¹⁄₀, p ²⁄₁, m ³⁄₃; total 32. Openings of male and female generative organs separated from the anal orifice; penis cylindrical or tapering; ear well developed; tail long, covered with equal or subequal hairs.
It has been shown by Brandt that the position of the premaxillo-maxillary sutures in the type of the genus is between the fourth and fifth tooth, so that it appears that we must regard this genus as differing from all other Eutherian mammals in having four upper incisors. Dr. Dobson, in his paper quoted, classes the tooth here reckoned as the upper canine with the premolar series in all the Shrews. Habits terrestrial. Species numerous, inhabiting the Palæarctic and Nearctic regions.
Of the two species found in the British Isles the Common Shrew (S. vulgaris, Fig. 287) is by far the most common in England, and is about the size of the House Mouse, to which it approximates in general form. The body is clothed with close long fur, very soft and dense, and varying in colour from light reddish to dark brown above, rarely speckled or banded with white. The under surface of both the body and the tail is grayish. The basal four-fifths of all the hairs above and beneath are dark bluish-gray; the hairs of the tail are less densely set and coarser. On each side of the body, at a point about one-third of the distance between the elbow and the knee, may be found, especially in the rutting season, a gland covered by two rows of coarse hairs. This secretes a peculiar fluid, on which the odour of the animal depends; this odour being evidently protective, and rendering the creature secure against the attacks of many predaceous animals.
The geographical range of the Common Shrew is exceedingly wide, extending eastwards through Europe and Asia (north of the Himalayas) to North America.
The Lesser Shrew (S. pygmæus[542]) is far less common in England and Scotland, although more abundant in Ireland, where S. vulgaris is unknown. It is distinguished from the latter not only by its inferior dimensions, but also by the circumstance that the third upper incisor is not longer than the fourth, and by the considerably shorter length of the forearm and manus. This species extends through Europe and Asia as far as the inland of Saghalin. Both this and the preceding species generally live in wooded districts, making their nests under the roots of trees, or in slight hollows. The great mortality noticeable among the Shrews in the early part of the autumn is probably due to insufficiency of food. The breeding season extends from the latter part of April to the beginning of August. The young, which are blind, naked, and toothless at birth, are very quickly developed. The number in a litter is usually from five to seven, but may be as many as ten.
The Alpine Shrew (S. alpinus), which is restricted to the Alpine region of Central Europe, is slightly larger than the common species, from which it is distinguished by the longer tail, the length of which exceeds that of the head and body, by the fur being dark on both surfaces of the body, and also by the larger size of the upper canine.
In North America S. bendirei is by far the largest species of the genus; and, as in many other species of the same country, the fourth upper incisor is relatively small. In S. hoyi (separated by some writers as Microsorex), of the same country, this tooth is rudimentary.
Other North American Shrews, which are regarded by some zoologists as generically distinct under the name of Neosorex, are aquatic, and thus take the place of the Old World genus Crossopus. These are S. palustris of the Rocky Mountains and S. hydrodromus of Unalaska Island, both of which resemble Crossopus in having the feet provided with swimming fringes, but agree with the other species of Sorex in their dentition and the character of the tail. The former species is about the size of Crossopus fodiens, while the latter is scarcely larger than S. pygmæus.
Soriculus.[543]—Dentition: i ⁴⁄₂, c ¹⁄₀, p ¹⁻²⁄₁, m ³⁄₃; total 30, or rarely 32. Opening of male or female generative organs forming with the anal orifice a shallow cloaca. Ear and tail as in Sorex. First upper incisor with an internal cusp. Habits terrestrial.
This genus is the only representative in the Oriental region of the Soricinæ, which are otherwise confined to the Palæarctic and Nearctic regions. The Indian and Burmese species comprise S. nigrescens, S. caudatus, and S. macrurus.
Notiosorex.[544]—Dentition: i ³⁄₂, c ¹⁄₀, p ¹⁄₁, m ³⁄₃; total 28. Tail moderate; first upper incisor without an inner cusp; other characters as in Soriculus. Habits terrestrial.
This American genus is represented by S. crawfordi and S. evotis, which are found in Central America and Mexico, and are thus some of the most southerly representatives of the Shrews in that continent. Their external appearance is very similar to that of the Old World genus Crocidura.
Blarina.[545]—Dentition: i ⁴⁻³⁄₂, c ¹⁄₀, p ²⁄₁, m ³⁄₃; total 32 or 30. Ear truncated above; tail short; otherwise as in Soriculus. This group of so-called Earless or Short-tailed Shrews is mainly North American, the common forms being B. dekayi and B. brevicauda. The species vary considerably in size; and B. mexicana and micrura extend the range of the genus into Mexico and Guatemala. The following account of the habits of B. brevicauda is taken from Dr. Merriam’s Mammals of the Adirondack Region: “The rigours of our northern winters seem to have no effect in diminishing its activity, for it scampers about on the snow during the severest weather, and I have known it to be out when the thermometer indicated a temperature of -20° Fahr. It makes long journeys over the snow, burrowing down whenever it comes to an elevation that denotes the presence of a log or stump, and I am inclined to believe that at this season it must feed largely upon the chrysalides and larvæ of insects that are always to be found in such places.” Dr. Merriam has made the interesting discovery that the common short-tailed North American Shrew supplements its insectivorous fare by feeding on beech-nuts, which will account for the generally very worn state of the teeth in this species.
Crossopus.[546]—Dentition: i ³⁄₂, c ¹⁄₀, p ²⁄₁, m ³⁄₃; total 30. Opening of male or female generative organs enclosed within the same ring as the anal orifice; penis broad, with lateral processes. Ears small, not truncated. Tail long, with an inferior fringe of elongated hair; feet also fringed. Habits aquatic. The Palæarctic Water-Shrew (C. fodiens) is considerably larger than the Common Shrew, from which it is readily distinguished externally by its shorter and much broader muzzle, comparatively smaller eyes, and larger feet adapted for swimming,—the sides of the feet and toes being provided with comb-like fringes of stiff hairs. The tail is longer than the body, and possesses a well-developed swimming fringe of moderately long, regularly arranged hairs, which extend along the middle of the flat under surface from the end of its basal third to its extremity. The fur of the body is long and very dense, varying much in colour in different individuals, and this has given rise to descriptions of many nominal species; the prevailing shades are dark brown, almost black, above, and more or less bright ashy tinged with yellowish beneath; sometimes in the same litter there are individuals with the under surface more or less dark coloured. In the number as well as in the shape of the teeth the Water-Shrew differs from the Common Shrew: there is a premolar less on each side above; the bases of the teeth are much more prolonged posteriorly; and their cusps are much less stained brown, so that in old individuals with worn teeth they often appear altogether white. This species resembles the otter in its aquatic habits, swimming and diving with great agility. It frequents rivers and lakes, making its burrows in the overhanging banks, from which when disturbed it escapes into the water. Its food consists of insects and their larvæ, small crustaceans, and probably the fry of small fishes. It is generally distributed throughout England, is less common in Scotland, and as yet it has not been recorded in Ireland; specimens have been obtained from many parts of Europe, and also from Asia as far eastward as the Altai Mountains.
Subfamily =Crocidurinæ=.—Teeth completely white.
Myosorex.[547]—Dentition: i ³⁄₂, c ¹⁄₀, p ²⁄₁₋₂, m ³⁄₃; total 30 or 32. Penis cylindroid and tapering; male or female generative organs opening close to anal orifice, but not forming a cloaca. Ears well developed; tail long, clothed with equal or subequal hairs. Habits terrestrial.
This genus is typically represented by M. varius, a very small Shrew from the Cape, which is quite unique among the whole family in having a rudimental seventh pair of lower teeth.
Crocidura.[548]—Dentition: i ³⁄₂, c ¹⁄₀, p ²⁻¹⁄₁, m ³⁄₃; total 28 or 30. Male or female generative organs forming a short cloaca with the anal orifice. Tail long, with a mixture of long and short hairs. Other characters as in Myosorex. Habits terrestrial.
This Old World genus includes over seventy nominal species, which have been divided into four subgenera, C. aranea and C. suaveolens of Continental Europe, and C. cœrulea of India, being well-known forms. The species are very variable and difficult to discriminate. C. aranea has a very wide distribution, ranging from Central and Southern Europe to North Africa and Central Asia. The name Musk-Rat is popularly applied in India to C. cœrulea, which frequents houses at night, hunting round rooms for cockroaches and other insects, and occasionally uttering a sharp shrill cry. The strong musky odour of this animal arises from large glands situated beneath the skin of the side of the body, a short distance behind the fore limbs. This odour is so powerful and penetrating that it is popularly believed in India that if the animal runs over a corked bottle of wine or beer it will infect the fluid within. Jerdon says that certainly many bottles are met with quite undrinkable from the peculiar musky odour of their contents, but, rejecting the possibility of its passing through the glass, he attributes it to the corks having been infected previously to bottling, stating in corroboration of this view that he has never found the odour in liquors bottled in England.
Diplomesodon.[549]—Dentition: i ²⁄₂, c ¹⁄₀, p ¹⁄₁, m ³⁄₃; total 26. Tail moderate; soles of the feet hairy. Other characters as in Crocidura. Habits terrestrial.
This genus is represented only by D. pulchellus of the Kirghiz steppes, which is allied to the following form, although retaining the normal Shrew-like external contour.
Anurosorex.[550]—Dentition: i ²⁄₂, c ¹⁄₀, p ¹⁄₁, m ³⁄₃; total 26. Ear very short; tail rudimental or short; soles of feet naked. Other characters as in Diplomesodon.
The two species of this genus are Mole-like terrestrial forms, of which the typical A. squamipes occurs in Tibet, while A. assamensis is found in Assam. The latter species has the longer tail. The habits of both are probably fossorial.
Chimarrogale.[551]—Dentition: i ³⁄₂, c ¹⁄₀, p ¹⁄₁, m ³⁄₃; total 28. Penis broad, with lateral processes; male or female generative organs opening within the same integumentary ring as the anal orifice. Tail long, with an inferior fringe of elongated hairs; ears small; plantar callosities simple; toes free. Habits aquatic.
This genus includes C. himalayica of the Himalaya and C. platycephalus of Japan. Both have the feet fringed, and, together with the next genus, may be regarded as the eastern analogues of Crossopus among the red-toothed series; their structural resemblances to the latter, if Dr. Dobson’s classification is a natural one, being probably due to adaptation for a similar mode of life.
Nectogale.[552]—Dentition: i ³⁄₂, c ¹⁄₀, p ¹⁄₁, m ³⁄₃; total 28. External ears not forming a conch, valvular. Plantar callosities forming adhesive pads; toes webbed. Other characters as in Chimarrogale. Habits aquatic.
The sole representative of this genus is the Tibetan Water-Shrew (N. elegans, Fig. 288), which differs from all other members of the family by the webbed toes and the presence of the disc-like adhesive pads on the under surface of the feet, which are believed to enable the creature to hold on to smooth rocks or stones in the beds of the streams it inhabits. This species is probably more completely aquatic in its habits than the allied Chimarrogale.
Fossil Soricidæ.—Remains of existing species of Sorex or Crossopus occur in the Norfolk Forest bed, while an extinct species has been found in the Pleistocene of Sardinia. Crocidura occurs in the cavern-deposits of Madras. Shrews from the Miocene and Upper Eocene of Europe have been referred to Sorex and the genus Amphisorex, which is a synonym of Crossopus.
Family TALPIDÆ.
Allied to the Soricidæ, but distinguished by the presence of a zygomatic arch and auditory bulla in the skull, and by the form of the teeth. The eyes are very small, and in some species covered with skin; the ears are short and concealed by the fur; the fore limbs are generally more or less modified for digging; there is no symphysis pubis; the intestine has no cæcum; the tibia and fibula are united; and the unicuspidate first upper and lower incisors are not extended horizontally forwards.
This family is connected with the Soricidæ by Urotrichus and Uropsilus. All the members are limited to the temperate regions of Europe, Asia, and North America; and the majority of them are of fossorial habits, although a few are aquatic or cursorial. The family has been divided into two subfamilies by Professor Mivart, and since this arrangement has been very generally adopted it will be followed here. From the presence of intermediate forms like Scaptonyx Dr. Dobson, in the second part of his Monograph of the Insectivora, has proposed a different arrangement, which, with the omission of some forms which are of not more than subgeneric value, is as follows:—
MYOGALÆ—Myogale. CONDYLURÆ—Condylura. SCALOPES { Scapanus. { Scalops. TALPÆ—Talpa. UROTRICHI { Scaptonyx. { Urotrichus. UROPSILI—Uropsilus.
Subfamily =Myogalinæ=.—Clavicles and humerus moderately elongated; manus without falciform bone.
Myogale.[553]—Dentition: i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 44. Feet webbed. Habits aquatic. This genus is represented by the two species M. moschata (Fig. 289) and M. pyrenaica, of which the former is by far the largest member of the family, its total length being about 16 inches. Its long proboscis-like snout projects far beyond the margin of the upper lip; the toes are webbed as far as the bases of the claws; and the long scaly tail is laterally flattened, so as to form a powerful instrument of propulsion when swimming. This species inhabits the banks of streams and lakes in South-East Russia, where its food consists of various aquatic insects. M. pyrenaica, living in a similar manner in the region of the Pyrenees, is very much smaller, has a round tail, and a proportionally longer snout. Fossil remains of M. moschata occur in the Norfolk Forest bed, and were originally described under the name of Palæospalax. The genus is also represented in the Middle and Lower Miocene of the Continent.
Urotrichus.[554]—Dentition: i ²⁄₁, c ¹⁄₁, p ⁴⁄₃ or ³⁄₄, m ³⁄₃; total 36. Feet not webbed; manus broad. Habits fossorial. The Mole-Shrews, as these animals are called, are represented by U. talpoides of the mountains of Japan and U. gibbsi of North America. These two species are small and closely allied animals; the American form (which it has been proposed to separate subgenerically as Neurotrichus) having p ³⁄₄.
Uropsilus.[555]—Dentition: i ²⁄₁, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 34. Manus narrow; tail naked and scaly. Habits cursorial. The single species, U. soricipes, from the borders of Tibet, is a slate-coloured animal with the external form of a Shrew but the skull of a Mole.
Subfamily =Talpinæ=.—Clavicle and humerus very short and broad; manus with a large falciform bone.
A. First upper incisor much larger than the second (New World Moles).
Scalops.[556]—Dentition: i ³⁄₂, c ¹⁄₀, p ³⁄₃, m ³⁄₃; total 36. Extremity of muzzle simple; hind feet webbed; tail short and nearly naked. Represented by three species in the United States.
Scapanus.[557]—Dentition: i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 44. Extremity of muzzle simple. The two North American species of this genus resemble Scalops in general characters, but have a dentition like Condylura. The habits are like those of the latter, and the right to generic distinction is doubtful.
Condylura.[558]—Dentition: i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 44. Extremity of muzzle surrounded by filiform appendages. The Star-nosed Mole (C. cristata) derives its name from the star-like ring of appendages at the extremity of the muzzle, with the nostrils in the centre. The general contour is Mole-like, but the tail is nearly as long as the body, and the manus is somewhat less powerful, with its terminal phalanges not cleft. The length of the head and body is about 5 inches. This species is common in parts of North America, and forms tunnels in the ground like the Common Mole.
B. First upper incisor scarcely larger than the second (Old World Moles).
Scaptonyx.[559]—Dentition: i ³⁄₂, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 42. Manus moderately broad, as in Urotrichus. Represented only by S. fusicaudatus of Eastern Tibet, which may be regarded as connecting Talpa with Urotrichus, having the head of the former and the limbs of the latter.
Talpa.[560]—Dentition (usually): i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; total 44. Manus extremely broad.
This genus includes the true Moles, of which the common English Mole[561] (T. europæa) is the type. This animal is about 6 inches in total length, of which rather more than one inch is occupied by the tail. The body is elongated and cylindrical, and, owing to the very anterior position of the fore limbs, the head appears to rest between the shoulders; the muzzle is long and obtusely pointed, terminated by the nostrils, which are close together; the minute eye is almost hidden by the fur; the ear is without a conch, and opens on a level with the surrounding integument. The fore limbs are rather short and very muscular, terminating in broad, naked, shovel-shaped feet, with the palms normally directed outwards, and each with five subequal digits armed with strong flattened claws. The hind feet are long and narrow, and the toes are provided with slender claws. The body is densely covered with soft, erect, velvety fur, the hairs being uniform in length and thickness, except on the muzzle and short tail. The colour of the fur is generally black, with a more or less grayish tinge, or brownish-black, but various paler shades up to pure white have been observed.
The food of the Mole consists chiefly of the earth-worm, in pursuit of which it forms its well-known underground excavations. Its habits were many years ago studied and described by M. Henri le Court. Like many other mammals, the Mole has a lair to which it may retire for security. This consists of a central nest formed under a hillock, placed in some protected situation, as under a bank, or between the roots of trees. The nest, which is lined with dried grass or leaves, communicates with the main run by four passages, of which only one joins it directly, leading downwards for a short distance and then ascending again. The other three are directed upwards and communicate at regular intervals with a circular gallery constructed in the upper part of the hillock, which in turn communicates by five passages leading downwards and outwards with another much larger gallery placed lower down on a level with the central nest, from which passages proceed outwards in different directions, one only communicating directly with the main run, while the others, curving round, either soon join or end blindly. The main run is somewhat wider than the animal’s body: its walls are smooth, and formed of closely compressed earth, the depth varying according to the nature of the soil, but ordinarily from 4 to 6 inches. Along this tunnel the animal passes backwards and forwards several times daily, and here traps are laid by mole-catchers for its capture. From the main run numerous passages are formed on each side, along which the animal hunts its prey, throwing out the soil in the form of mole-hills. The Mole is one of the most voracious of mammals, and, if deprived of food, is said to die in from ten to twelve hours. Almost any kind of flesh is eagerly devoured by captive Moles, which have been seen by various observers, as if maddened by hunger, to attack animals nearly as large as themselves, such as birds, lizards, frogs, and even snakes; toads, however, they will not touch, and no form of vegetable food attracts their notice. If two Moles be confined together without food, the weaker is invariably devoured by the stronger. Moles take readily to the water, in which respect they resemble their representatives on the North American continent. Bruce, writing in 1793, remarks that he saw a Mole paddling towards a small island in the Loch of Clunie, 180 yards from land, on which he noticed mole-hills.
The sexes come together about the second week in March, and the young—generally from four to six in number—which are brought forth in about six weeks, quickly attain their full size.
The Mole exhibits in the whole of its organisation a perfect adaptation to its peculiar mode of life. In the structure of the skeleton (Fig. 290) very striking departures from the typical mammalian form are noticeable. Thus the presternum is so much produced anteriorly as to extend forward as far as a vertical line from the second cervical vertebra, carrying with it the very short and almost quadrate clavicle, which is articulated with its anterior extremity and distally with the humerus; being also connected ligamentously with the scapula. The fore limbs are thus brought opposite the sides of the neck, and from this position a threefold advantage is derived: in the first place, as this is the narrowest part of the body, they add but little to the general width, which if increased, would lessen the power of movement in a confined space; secondly, this position allows of a longer fore limb than would otherwise be possible, and so increases its power; and, thirdly, although the entire limb is relatively very short, its anterior position enables the animal, when burrowing, to thrust the claws so far forward as to be in a line with the end of the muzzle, the importance of which is evident. Posteriorly, the hind limbs are similarly removed out of the way by approximation of the hip-joints to the centre line of the body. This is effected by inward curvature of the innominate bones at the acetabula to such an extent that they almost meet in the centre, while the pubic bones are widely separated behind. The shortness of the fore limb is caused by the great reduction in the length of the humerus, which has lost all resemblance to its normal shape. In addition to the usual articulation with the glenoid cavity of the scapula, the humerus also has a separate articulation with the extremity of the clavicle. The bones of the manus are enormously expanded laterally; this expansion being increased by the large sickle-like bone on the radial side of the carpus, which is considered by some anatomists to represent the prepollex. The skull is long and tapering, with very slender zygomatic arches and elongated nasals, which are ankylosed together, and in advance of which the mesethmoid is more or less ossified. The vertebræ are usually C 7, D 13, L 6, S 6, C 10-12; all having very strong surfaces for mutual articulation. The upper incisors are chisel-like, and the canine has two roots; the first three upper premolars are simple and conical, but the fourth is much larger, and canine-like. In the mandible the incisors are small and somewhat proclivous, while the canine can only be distinguished from them by its position: the first lower premolar is larger than the others.
The Common Mole has an exceedingly wide distribution, ranging over the greater part of the Palæarctic region, where it is met with in places so widely sundered as England and Japan. It occurs in both the Himalaya and Altai mountains. In Ireland it is unknown, and in Scotland it extends as far north as Caithness. Eight species of the genus are recognised, which may be grouped, from the characters of their dentition, as follows, viz.: i ³⁄₃, c ¹⁄₀, p ⁴⁄₄, m ³⁄₃, T. wogura; i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃, T. europæa, cæca, longirostris, micrura; i ³⁄₃, c ¹⁄₁, p ³⁄₄, m ³⁄₃, T. leucura, leptura; i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃, T. moschata.
Except in T. europæa, the eyes are covered by a membrane. In T. micrura the short tail is concealed by the fur. T. cæca is found south of the Alps; the remaining species are Asiatic, and two only—T. micrura and T. leucura—occur south of the Himalaya. T. moschata, of Tibet, is regarded by some zoologists as generically distinct under the name of Scaptochirus.
Remains of T. europæa occur in the Norfolk Forest bed, while extinct species are found in the European Tertiaries as far down as the Lower Miocene, although it has been proposed to separate some of these forms generically. Protalpa, of the Upper Eocene Phosphorites of Central France, is very closely allied, but the structure of the humerus is somewhat less specialised.
Extinct Genera.—A number of extinct Insectivora from the European Tertiaries more or less closely allied to the Moles have been described, but since our knowledge of most of them is extremely imperfect their precise affinities are in many instances problematical. Of these, the Lower Miocene Tetracus is said to have affinity both with Myogale and Erinaceus; while the forms described as Mysarachne and Echinogale, are considered to connect the present with the two preceding families. Plesiosorex is another Lower Miocene type known only by the mandible, in which there are ten teeth; it is generally referred to the Myogalinæ. The minute Amphidozotherium, of the French Phosphorites, is considered to be allied to Urotrichus.
Family ADAPISORICIDÆ.
This extinct family is represented by the genera Adapisorex and Adapisoriculus, of the lowest Eocene of Rheims, which are regarded as allied to the Soricidæ, but somewhat more specialised. In the type genus the formula of the lower teeth is i 2, c 1, p 4, m 3; the incisors and canine being proclivous, and the molars (of which the last is small and without a third lobe) quadritubercular. Adapisoriculus is a smaller form with differently shaped molars.
Here also may be mentioned the genera Orthaspidotherium and Pleuraspidotherium, from the above-mentioned deposits, which are probably members of the present order. They appear to have been animals somewhat smaller than a Hedgehog, with quadritubercular upper molars (Fig. 291), and the hinder premolars more complex than those of the Erinaceidæ. In the first-named genus the dental formula is i ³⁄₃, c ¹⁄₁, p ⁴⁄₄, m ³⁄₃; the third and fourth upper premolars having one outer column. Pleuraspidotherium has apparently only three premolars, of which the third and fourth (Fig. 291) have two outer columns. The humerus in both has no entepicondylar foramen, the femur has a third trochanter, and the astragalus is vertically perforated.
Family POTAMOGALIDÆ.
Skull with a small brain-case, no zygomatic arch or postorbital process, and the tympanic annulate and not forming a bulla. Upper molars with the cusps arranged in a broad V, and somewhat intermediate in structure between those of the preceding and succeeding families. No clavicle; pubic symphysis ligamentous; tibia and fibula typically united distally. No cæcum. Confined to the Ethiopian region.
Potamogale.[562]—Dentition: i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 40. Represented only by P. velox of Western Equatorial Africa. This animal (Fig. 292) inhabits the banks of streams, and is thoroughly adapted for an aquatic life; it is nearly 2 feet in length, the tail measuring about half. The long cylindrical body is continued uninterruptedly into the thick laterally compressed tail, the legs are very short, and the toes are not webbed, progression through the water evidently depending wholly on the action of the powerful tail, while the limbs are folded inwards and backwards. The muzzle is broad and flat, and the nostrils are protected by valves. The fur is dark brown above, the extremities of the hairs on the back being of a metallic violet hue by reflected light, beneath whitish. This curious animal was discovered by M. du Chaillu.
Geogale.[563]—Dentition: i ²⁄₂, c ¹⁄₁, p ³⁄₂, m ³⁄₃; total 34. This genus is known solely by G. aurita, a small Mouse-like species from Madagascar, agreeing closely with Potamogale in the general form of the skull and teeth. The tibia and fibula are distinct, but it is not known whether a clavicle exists; and the material at present available is insufficient to definitely fix the natural position of the genus.
Family SOLENODONTIDÆ.
Skull with a small brain-case constricted between the orbits, no zygomatic arch or postorbital process, and the tympanic annulated and not forming a bulla. Upper molars tritubercular, the cusps being arranged in a V. Pubic symphysis short; tibia and fibula distinct. Vertebræ: C 7, D 15, L 4, S 5, C 23. No cæcum. The penis is carried forwards and suspended from the abdomen; the testes are received into perineal pouches; the mammary glands are post-inguinal; the uterine cornua end in cæcal sacs.
Solenodon.[564]—Dentition: i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 40. This genus, with S. paradoxus and S. cubanus (Fig. 293), from Hayti and Cuba respectively, alone represents the family. These species, which differ chiefly in the colour and quality of the fur, have a remarkably long cylindrical snout, a long naked tail, feet formed for running, and the body clothed with long, coarse fur.
The position of the mammæ quite behind on the buttocks is unique among Insectivora. The first upper incisor is much enlarged, and this and the other incisors, canines, and premolars, closely resemble those of Myogale; the second lower incisor is, as in Potamogale, much larger than the anterior one, and is deeply hollowed out internally. While thus apparently showing relationship with the Talpidæ, the form of the crowns of the molar teeth connects them with the next family.
Family CENTETIDÆ.
Skull (Fig. 294) with a small cylindrical brain-case not constricted between the orbits, no zygomatic arch or postorbital process, and the tympanic annulate and not forming a bulla. Upper molars tritubercular. Pubic symphysis short; and the tibia and fibula either united or free. No cæcum. The penis is pendent and retractile within the fold of the integument surrounding the anus; the testes are abdominal; the mammæ are thoracic and ventral; and the uterine cornua are terminated by the Fallopian tubes. All the species are limited to Madagascar.
Subfamily =Centetinæ=.—Tibia and fibula distinct; testes near kidneys; fur with spines.
Centetes.[565]—Dentition: i ²⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 38. Vertebræ: C 7, D 19, L 5, S 3, C 8. The single species is the well-known Tenrec (C. ecaudatus), characterised by the absence of a tail; it reaches a total length of from 12 to 16 inches, and is the largest known Insectivore. The adult males have long canines, the extremities of the lower pair being received into pits in front of the upper ones (Fig. 294). It is probably the most prolific of all mammals, since as many as twenty-one young are said to have been brought forth at a birth. The young have strong white spines arranged in longitudinal lines along the back, but these are lost in the adult animal, which is provided only with a nuchal crest of long rigid hairs. In rare instances a fourth upper molar may be developed.
Hemicentetes.[566]—Dentition: i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 40. This genus is represented by the two species H. semispinosus (of which the skull is shown in Fig. 295) and H. nigriceps. It differs from Centetes by the presence of the third upper incisor, the much smaller canines, and by the form of the skull. Both species are very much smaller than C. ecaudatus, and the dorsal spines are retained in the adult state. Vertebræ: C 7, D 16, L 5, S 3, C 9.
Ericulus.[567]—Dentition: i ²⁄₂, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 36. Vertebræ: C 7, D 17, L 6, S 4, C 9. The single species, E. setosus, is a Hedgehog-like animal, having the whole upper surface and the short tail densely covered with close-set spines. The facial bones are much shorter than in any of the preceding genera, and the first upper incisor is elongated, as in Erinaceus. Judging from the slight development of the cutaneous muscles compared with those of the true Hedgehogs, it is probable that complete involution of the body does not take place.
Subfamily =Oryzorictinæ=.—Tibia and fibula united; testes near urethra; fur without spines.
Microgale.[568]—Dentition: i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 40. This genus includes M. longicaudata and M. cowani, both of which are small Mouse-like species, the former with a tail double the length of the head and body, and having 43 caudal vertebræ; teeth like those of Centetes ecaudatus, but, owing to the comparatively much shorter muzzle, not separated by wide spaces, and the last premolar and molar with internal basal processes.
Oryzorictes.[569]—Represented by two species, O. hova and O. tetradactylus, the latter distinguished by the presence of only four digits in the manus, the three inner having long laterally compressed fossorial claws. The general form of the head and body of the two species known is like that of a Mole. These animals burrow in the rice-fields and do much damage to the crops.
Family CHRYSOCHLORIDÆ.
Skull conical, not constricted between the orbits, without postorbital process, but with well-developed zygomatic arch and tympanic bulla. Upper molars tritubercular, with the crowns very tall. No pubic symphysis; the tibia and fibula united. The eyes are covered by the hairy integument; the ears short and concealed by the fur; the internal generative organs are as in Centetinæ; the mammæ are thoracic and inguinal and placed in cup-shaped depressions. Habits fossorial. Confined to the southern part of the Ethiopian region, not extending to Madagascar.
This family is closely allied to the Centetidæ, occupying the same relative position with respect to that family that the Talpidæ does to the Soricidæ. Compared with the Talpidæ, we find the following differences in the structural adaptation to a fossorial life; the manubrium sterni is not anteriorly elongated, neither are the clavicles shortened; but this is compensated for by a deep hollowing out of the antero-lateral walls of the thorax, the ribs in these parts and the sternum being convex inwards. The long clavicles have their distal extremities pushed forward, and the concavities on the sides and inferior surface of the thorax lodge the thick muscular arms.
Chrysochloris.[570]—Dentition: i ³⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁻²⁄₃₋₂; total 40 or 36. Vertebræ: C 7, D 19, L 3, S 5, C 8. This genus includes some seven or eight South African species, commonly known as Golden Moles (Fig. 296). Those species, in which the molars are reduced to ²⁄₂, with a basal talon to the lower ones, and without a prominence in the temporal fossa, have been placed in a separate genus, Chalcochloris, by Professor Mivart. Nearly all the species have the fur of the upper surface of a brilliant metallic lustre, varying from golden bronze to green and violet of different shades. The manus has four digits, of which the two outer are small, while the middle ones are large, with immensely powerful claws.
Extinct Types.—The only fossil forms which can be referred to the section of the Insectivora with tritubercular molars are the Leptictidæ, of the Eocene and Miocene of North America. This family includes the genera Leptictis, Mesodectes, and Ictops, all of which are regarded by Dr. Schlosser as true Insectivora, although they were placed by Professor Cope with the Creodont Carnivora.
Bibliography of Insectivora.—Peters, Reise nach Mossambique—Säugeth. 1852; Id. “Ueber die Classification der Insectivora,” Monatsb. Akad. Wissensch. Berlin, 1865, and other papers; Mivart, “On the Osteology of Insectivora,” Journ. Anat. and Phys. 1867, 1868, and Proc. Zool. Soc. 1871; Gill, “Synopsis of Insectivorous Mammals,” Bull. Geol. and Geog. Survey, U.S.A. Washington, 1875 (includes a general bibliography of the order); Dobson, Monograph of the Insectivora, Systematic and Anatomical, London, 1882-90.
XIII. THE ORDER CHIROPTERA
Mammals, having their fore limbs specially modified for flight. The forearm consists of a rudimentary ulna, and a long curved radius. The carpus has six bones supporting a small pollex and four greatly elongated fingers, between which and the sides of the body and the hinder extremities a thin expansion of the integument (the wing-membrane or patagium) is extended. The knee is directed backwards, owing to the rotation of the hind limb outwards by the wing membrane; a peculiar elongated cartilaginous process (the calcar), rarely rudimentary or absent, arising from the inner side of the ankle-joint, is directed inwards, and supports part of the posterior margin of an accessory membrane of flight, extending from the tail or posterior extremity of the body to the hinder limbs (the interfemoral membrane). The penis is pendent; the testes are abdominal or inguinal; the mammary glands thoracic and generally postaxillary; the uterus is simple or with more or less long cornua; the placenta discoidal and deciduate; and the smooth cerebral hemispheres do not extend backwards over the cerebellum. The dental series includes incisors, canines, premolars, and molars and never exceeds i ²⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 38.
The animals comprised in this order are at once distinguished by the presence of true wings, and this peculiarity is accompanied by other modifications of bodily structure having special relation to flight. Thus, in contrast to most other mammals, in which the hind limbs greatly preponderate in size over the fore, in the present order the fore limbs immensely exceed the short and weak hinder extremities. The thorax, as giving origin to the great muscles which sustain flight, and containing the proportionately large lungs and heart, is remarkably capacious, and the ribs are flattened and close together; the shoulder-girdle is also greatly developed in comparison with the weak pelvic bones.
Linnæus included the Bats among the Primates, mainly on account of the number of their upper incisors, supposed to be always four, the thoracic position of the mammæ, and the pendent condition of the penis. Many other zoologists, taking into consideration the placental characters and the form of the uterus, have followed him; but it is evident that the situation of the mammæ is related to the necessarily central position of the young during flight, the shortness of the uterine cornua, observable in so many species, to the generally uniparous gestation requiring less room, while the discoidal deciduate placenta is equally present in and characteristic of the Insectivora, many species of which also have the penis pendent. Thus, the reasons for maintaining the Bats in this high position being disposed of, we find in the low organisation of their brain a proof of their inferior status; while furthermore, although they differ widely from all other mammals in external form, it is evident that this is only the result of special adaptation to aerial locomotion; and, taking into account their whole bodily structure, we may accept the view of Professor Huxley that they should merely be regarded as exceedingly modified Insectivora.
So thoroughly, however, has this adaptation for flight been carried out that of all animals the Bats are the least terrestrial, not one of them being equally well fitted for progression on the earth. This is due to the hind as well as the fore limbs being pressed into the service of aerial locomotion. Thus the hind limb is so rotated outwards by the wing-membrane that, contrary to what obtains in all other vertebrates, the knee is directed backwards, and corresponds in position to its serial homologue the elbow. It necessarily follows from this arrangement that when a Bat is on the ground it rests on all fours, having the knees directed upwards; while, in order to bring it into a position for forward progression, the foot rotates forwards and inwards on the ankle. Walking under these circumstances is at best only a kind of shuffle, and that this is fully recognised by the animal is evidenced by its great anxiety to take wing, or, if this be impracticable, to ascend to some point where it can hitch itself up by the claws of the hind legs in its usual position when at rest.
The bones of the skeleton are characterised by their slenderness and the great size of the medullary canals in those of the extremities. The vertebral column is short, and the vertebræ differ very slightly in number and form throughout the species. The general number of the dorso-lumbar vertebræ is 17, of which 12 are dorsal; the cervicals are very broad, but short from before backwards, their breadth being due to the great transverse diameter of the spinal canal rendered necessary by the comparatively large size of the spinal cord, which, after giving off the nerves to the fore limbs and thorax, rapidly diminishes in size, and in the lumbo-sacral region is reduced to a fine thread. Except in the frugivorous Pteropodidæ, the vertebræ, from the third cervical backwards, are devoid of neural spines. From the first dorsal to the last lumbar vertebra the spinal column forms a single curve backwards, which is most pronounced in the lumbar region. The centra of the vertebræ are but slightly movable upon each other, and in old individuals appear to become partially ankylosed together. The caudal vertebræ are simple cylindrical bones without processes; their number and length being extremely variable even in closely allied species; and the anterior caudals are generally united to the ischial tuberosities. The relative development of the caudal vertebræ is, indeed, intimately correlated to the habits of the animals; the long tail in the insectivorous forms supporting and controlling the position of the large interfemoral membrane, which appears not only to aid their rapid motions when in pursuit of their prey by acting as a rudder, but also to assist in the capture and retention of the larger insects. In the frugivorous types, on the other hand, this is not required, and the tail is accordingly rudimentary or absent. In all Bats the presternum has a prominent keel for the attachment of the great pectoral muscles. In most species the ribs are much flattened, and in some they are partially ankylosed by their contiguous margins.
The skull is subject to considerable structural variations, even within the limits of a single family. Postorbital processes to the frontals are found only in the Pteropodidæ, and some Nycteridæ and Emballonuridæ. Pteropus leucopterus and Pteralopex are peculiar in having the orbit completely surrounded by bone. A slender zygomatic arch is present, except in some of the Phyllostomatidæ.
The milk-teeth are peculiar in that they are utterly unlike those of the permanent series. They are slender, with sharp recurved cusps; and as a rule are shed at an early period (in the Rhinolophidæ before birth), but may coexist with some of the fully developed permanent teeth. The permanent teeth are subject to great variation of form, although they always have distinct roots. In the Insectivorous types they are acutely cusped, the cusps in those of the upper jaw being arranged in a more or less distinct W; but in the frugivorous forms, like the Pteropodidæ and some of the Phyllostomatidæ, the molars are longitudinally grooved or hollowed out.
The pectoral girdle maintains a very constant type. Thus the clavicle is very long, strong, and curved; and the scapula large, oval, triangular, with a long curved coracoid process. The humerus, though long, is scarcely two-thirds the length of the radius. The ulna is rudimentary, its proximal extremity, which articulates with but a small part of the humerus, being ankylosed to the radius; and immediately beyond the joint it is reduced to a slender splint-like bone, extending about as far as the middle of the radius. In all species a detached sesamoid bone exists in the tendon of the triceps muscle. The radius is very long, in some species actually equal to the length of the head and body. The proximal row of the carpus consists of a single bone formed by the united scaphoid, lunar, and cuneiform; which, with the extremity of the radius, forms the radio-carpal joint. In the distal row the trapezium, trapezoid, and magnum vary in size in the different families, the unciform appearing to be the most constant, and the pisiform being generally very small.
The manus is always furnished with five digits. The first, fourth, and fifth digits consist of a metacarpal and two phalanges; but in the second and third digits the number of phalanges is different in certain families. The pollex always terminates in a claw, which—like the proximal phalanx—is best developed in the frugivorous species. In most of the frugivorous Pteropodidæ the second digit is provided with a claw; but in all other Bats this and the remaining digits are unarmed. In the genus Triænops alone a very peculiar short bony process projects from the outer side of the proximal extremity of the terminal phalanx of the fourth digit. The relative development of the digits and their phalanges will be noticed under each family.
As might be expected from the small size of the posterior limbs, the pelvic girdle is relatively weak. The ilia are long and narrow. In the males of most species the pubic bones of opposite sides are very loosely united in front, while in females they are widely separated; and in the family Rhinolophidæ alone do these bones form a symphysis. The ileo-pectineal eminence develops a long pectineal process, which in the subfamily Hipposiderinæ is continued forwards to the anterior extremity of the ilium enclosing a preacetabular foramen unique among mammals. The acetabulum is small and directed outwards and slightly upwards; and with this is related the peculiar position of the hind limb already noticed as one of the chief characteristics of the order. The femur is slender and cylindrical, with a small head and very short neck, and scarcely differs in form throughout the order. The bones of the leg and foot are variable; in the subfamily Molossinæ alone is there a well-developed fibula, while in all other species this bone is either very slender, or cartilaginous and ligamentous in its upper third, or reduced to a small bony process above the heel, as in Megaderma, or altogether absent, as in Nycteris.
The foot consists of a very short tarsus, and of slender, laterally compressed toes, with much curved claws. The hallux is composed of a metacarpal, a proximal and an ungual phalanx, and is slightly shorter than the other four toes, each of which has an additional phalanx, except in the subfamily Hipposiderinæ and in the anomalous genera Thyroptera and Myxopoda, where all the toes have the same number of phalanges as the first digit, and are equal to it in length. In the genus Chiromeles the first digit is thumb-like and separated from the others, and in the typical Molossinæ the first and fifth digits are much thicker than the intermediate toes.
The most noticeable peculiarities in the myology of the order consist in the separated bands or slips into which the platysma is divided, and in the presence of the remarkable muscle termed occipito-pollicalis, which extends from the occipital bone to the base of the terminal phalanx of the pollex.
Although, as already mentioned, the brain presents a low type of organisation, yet probably no animals possess so delicate a sense of touch as the Chiroptera. It is undoubtedly this perceptive power which enabled the individuals deprived of sight, hearing, and smell, in Spallanzani’s well-known experiments, to avoid the numerous threads hung across the rooms in which they were permitted to fly about. In the common Bats the tactile organs evidently exist, not only in the delicate vibrissæ which spring from the sides of the muzzle, but also in the highly sensitive and widely extended integumentary structures entering into the formation of the wing-membranes and ear-conchs; while in many other species, notably in the tropical Rhinolophine and Phyllostomatine Bats, peculiar foliaceous cutaneous expansions surrounding the nasal apertures or extending backwards behind them are added. These structures, collectively known as the “nose-leaf” (whence the term “leaf-nosed Bats”), have been shown by Dr. Dobson to be made up partly of the extended and thickened marginal integument of the nostrils, and partly of the highly differentiated glandular eminences occupying the sides of the muzzle, in which, in all the common Bats, the vibrissæ are implanted.
In all species of leaf-nosed Bats, and especially in the Rhinolophidæ, where the nasal appendages reach their highest development, the superior maxillary division of the fifth nerve is of remarkably large calibre. The nasal branch of this nerve, which is given off immediately beyond the infraorbital foramen, is by far the largest portion; the palpebral and labial branches consisting of a few slender nerve-fibres only. This branch passes forwards and upwards on the side of the maxilla, but soon spreads out into numerous filaments extending into the muscles and integument above, and into the base of the nose-leaf. The nerve supply of the nose-leaf is further augmented by the large nasal branch of the ophthalmic division of the fifth nerve. While the many foliations, elevations, and depressions which vary the form of the nose-leaf greatly increase the sensory surface supplied by the fifth nerve, and during rapid flight intensify the vibrations conveyed to it, the great number of sweat and oil glands which enter into its structure perform a function analogous to that of the glands of the auditory canal in relation to the membrana tympani in maintaining its surface in a highly sensitive condition. The nasal appendages of the Chiroptera may thus be regarded as performing the office of an organ of a very exalted sense of touch standing in the same relation to the nasal branches of the fifth nerve as the aural apparatus to the auditory nerve; for, as the latter organ collects and transmits the waves of sound, so the former receives impressions arising from vibrations communicated to the air by approaching objects.
In no order of mammals is the ear-conch so greatly developed or so variable in form. Thus in most of the insectivorous species the ears are longer than the head, while in some, as in the common Long-eared Bat (Plecotus auritus), their length nearly equals that of the head and body. The form of the conch is very characteristic of the various families; in most the tragus is remarkably large, in some extending nearly to the outer margin of the conch; and its function appears to be to cause undulations in the waves of sound, and so intensify and prolong them. It is worthy of notice that in the Rhinolophidæ, the only family of insectivorous Bats wanting the tragus, the auditory bullæ reach their greatest size, and the highly sensitive nasal appendages their highest development; and that in the typical group of the Molossinæ the ear-conch is divided by a prominent keel; and the antitragus is unusually large in those species in which the tragus is minute (see Fig. 298, a). In the frugivorous Bats the form of the ear-conch is very simple, and but slightly variable, throughout the various types.
In all Bats the ears are extremely mobile, each moving independently at the will of the animal. This has been observed even in the frugivorous Pteropodidæ, in which the peculiar vibratory movements first noticed in Artibeus perspicillatus may also be seen when the animals are alarmed.
The opening of the mouth is anterior in most species, but in many it is inferior, the extremity of the nose being more or less produced beyond the lower lip,—so much so indeed in the small South-American species Rhynchonycteris naso as to resemble that of the Shrews. The lips exhibit the greatest variety in form, which will be referred to under each family. The absence of a fringe of hairs is characteristic of all fruit-eating Bats, and probably always distinguishes them from the insectivorous species, which they may resemble in the form of their teeth and other respects.
The œsophagus is narrow in all species, and especially so in the sanguivorous Desmodont Phyllostomatidæ. The stomach presents two principal types of structure, which correspond respectively to the two great divisions of the order, the Megachiroptera and the Microchiroptera; in the former (with the exception of Harpyia) the pyloric extremity is more or less elongated and folded upon itself, in the latter it is simple, as in the Insectivora Vera; a third exceptional type is met with in the Desmodont Phyllostomatidæ, where the left or cardiac extremity is greatly elongated, forming a long narrow cæcum-like appendage. The intestine is comparatively short, varying from one and a half to four times the length of the head and body, being longest in the frugivorous and shortest in the insectivorous species. Only in Rhinopoma microphyllum and Megaderma spasma has a very small cæcum been found.
The liver is characterised by the great size of the left lateral lobe, which occasionally equals half the size of the whole organ; the right and left lateral fissures are usually very deep; in the Megachiroptera (Harpyia excepted) the Spigelian lobe is ill-defined or absent, and the caudate is generally very large; but in the Microchiroptera, on the other hand, the Spigelian lobe is very large, while the caudate is small, in most species forming a ridge only. The gall-bladder is generally well developed and attached to the right central lobe, except in the Rhinolophidæ, where it is connected with the left central.
In most species the hyoids are simple, consisting of a chain of slender, elongated, cylindrical bones connecting the small basi-hyoid with the cranium, while the pharynx is short, the larynx shallow with feebly developed vocal cords, and guarded by a short, acutely-pointed epiglottis, which in some genera (Harpyia, Vampyrus) is almost obsolete. In Epomophorus, however, we find a remarkable departure from the general type. Thus the pharynx is long and very capacious; the aperture of the larynx is far removed from the fauces, and, opposite to it, opens a canal, leading from the narial chambers, and extending along the back of the pharynx; the laryngeal cavity is spacious and its walls are ossified; the hyoid bone is quite unconnected, except by muscle, with the cranium; the ceratohyals and epihyals are cartilaginous and greatly expanded, entering into the formation of the walls of the pharynx, and in the males of three species at least, supporting the orifices of a large pair of air-sacs communicating with the pharynx (Fig. 299).
In extent, peculiar modifications, and sensitiveness the cutaneous system reaches its highest development in this order. As a sensory organ its chief modifications in connection with the external ear and with the nasal and labial appendages have been described when referring to the nervous system. It remains therefore to consider its relative development as part of the organs of flight.
The extent and shape of the flying-membranes depend mainly on the form of the bones of the anterior extremities, and on the presence or absence of the tail. Certain modifications of these membranes, however, are met with which do not depend on the skeleton, but are related to the habits of the animals, and to the manner in which the wing is folded in repose.
These membranes consist of the “antebrachial membrane,” extending from the point of the shoulder along the humerus and more or less of the forearm to the base of the pollex, the metacarpal bone of which is partially or wholly included in it; the “wing-membrane,” which is spread out between the greatly elongated fingers, and extends along the sides of the body to the posterior extremities, generally reaching to the feet; and the “interfemoral membrane,” the most variable of all, which is supported between the extremity of the body, the legs, and the calcar (Fig. 297).
The antebrachial and wing-membranes are most developed in those species fitted only for aerial locomotion, which when at rest hang with the body enveloped in the wings; but in the family Emballonuridæ, and especially in the subfamily Molossinæ (the species of which are the best fitted of all Bats for terrestrial progression), the antebrachial membrane is reduced to the smallest size, and is not developed along the forearm, leaving also the pollex quite free, and the wing-membrane is very narrow and folded in repose completely under the forearm. The relative development of the interfemoral membrane has been referred to above in describing the caudal vertebræ. Its small size in the frugivorous and sanguivorous species, in which its presence would be injurious as impeding their motions when searching for food as they hang suspended by their feet, is easily understood. Odoriferous glands and pouches opening on the surface of the outer skin are developed in many species, but in most cases more so in males than in females, and thus constitute secondary sexual characters, which will be referred to when treating of the peculiarities of certain species.
All the fossil Chiroptera at present known are true Bats in every sense of the word, and therefore throw no light on the origin of the order. The earliest representatives of the order occur in beds of Upper Eocene (Lower Oligocene) age.
The order is divided by Dobson into the suborders Megachiroptera and Microchiroptera.
Suborder MEGACHIROPTERA.
Frugivorous Bats, generally of large size. Crowns of molars smooth, marked with a longitudinal groove (cuspidate in Pteralopex); bony palate continued behind the last molar, narrowing slowly backwards; three phalanges in the index finger, the third phalanx generally terminated by a claw; sides of the ear-conch forming a complete ring at the base; tail, when present, inferior to (not contained in) the interfemoral membrane; pyloric extremity of the stomach generally much elongated; the Spigelian lobe of the liver ill-defined or absent, and the caudate well developed.
Limited to the tropical and subtropical parts of the eastern hemisphere.
Mr. O. Thomas[571] considers that the ordinary type of molar dentition found in this suborder is a specialised adaptation from the cuspidate type of the Microchiroptera; the genus Pteralopex retaining the ancestral form of teeth.
Family PTEROPODIDÆ.
Since all the forms are included in this family its characters may be taken to be the same as those of the suborder.
Subfamily =Pteropodinæ=.—Tongue moderate; molars well developed.
Epomophorus.[572]—Dentition: i ²⁻¹⁄₂, c ¹⁄₁, p ²⁄₃, m ¹⁄₂; total 28 or 26. Tail absent or very short, when present free from interfemoral membrane; second digit of manus clawed; premaxillæ united. This genus includes some seven species inhabiting Africa south of the Sahara. The head is large and long, and the lips are expansible, and frequently with peculiar folds. The ears have a white tuft of hair on the margin; and in the males of most species there are large glandular pouches in the skin of the side of the neck near the shoulder, from the mouth of which project long and coarse yellowish hairs, forming tufts on the shoulders, from which the genus takes its name. Another male secondary sexual character consists in the presence of a pair of large air-sacs extending outwards on each side from the pharynx beneath the integument of the neck, in the position shown in Fig. 299. These sacs are evidently capable of being greatly distended at the will of the animal, and their inflation probably occurs under the same circumstances that the wattles of male gallinaceous birds swell up, namely, when engaged in courting the females. Other remarkable conditions in which these Bats appear to differ from all other species occur in the form of the hyoid bones and larynx. These Bats appear to live principally on figs, the juicy contents of which their large lips and capacious mouths enable them to swallow without loss.
Pteropus.[573]—Dentition: i ²⁄₂, c ¹⁄₁, p ³⁄₃, m ²⁄₃; total 34. This genus has more than forty species, and thus includes more than half the members of the family. All are of large size, and the absence of a tail, the long pointed muzzle (Fig. 301), and the woolly fur covering the neck render their recognition easy. They are commonly known as “Flying Foxes,” or Fox-Bats; and one of the species (P. edulis) inhabiting Java measures 5 feet across the fully extended wings, and is thus the largest known species of the order. All the species closely resemble one another in dentition, and are mainly distinguished by the form of the ears and the quality of the fur. P. scapulatus, from North-East Australia, approaches the species of the second subfamily in the remarkable narrowness of its molars and premolars.
The range of this genus extends from Madagascar and the neighbouring islands through the Seychelles to India, Ceylon, Burma, the Malay Archipelago, Southern Japan, New Guinea, Australia, and Polynesia (except the Sandwich Islands, Ellice’s Group, Gilbert’s Group, Tokelau, and the Low Archipelago). Of the islands inhabited by it some are very small and remote from any continent, such as Savage Island in the South Pacific and Rodriguez in the Indian Ocean. Although two species inhabit the Comoro Islands, which are scarcely 200 miles from the African coast, not a single species is found in Africa; but in India, separated by thousands of miles of almost unbroken ocean, a species exceedingly closely allied to the common Madagascar Fox-Bat is abundant. The Malay Archipelago and Australia are their headquarters; and in some places they occur in countless multitudes. Mr. Macgillivray remarks of P. conspicillatus: “On the wooded slope of a hill on Fitzroy Island I one day fell in with this Bat in prodigious numbers, looking while flying in the bright sunshine (so unusual for a nocturnal animal) like a large flock of rooks. On close approach a strong musky odour became apparent, and a loud incessant chattering was heard. Many of the branches were bending under their load of Bats, some in a state of inactivity, suspended by their hind claws, others scrambling along among the boughs, and taking to wing when disturbed.”
Xantharpyia.[574]—Dentition as in Pteropus, but a short tail present, and the fur on the back of the neck similar to that of the body. This genus is represented by some nine species, which have a distribution very similar to that of Pteropus, except that they extend into Africa, and are not found in Australia and Polynesia. X. ægyptiaca inhabits the chambers of the Great Pyramid and other deserted buildings in Egypt, and is probably the species so generally figured in Egyptian frescoes. Fig. 302 exhibits an African species of this genus in the attitude assumed by the Fox-Bats when at rest.
Boneia.[575]—This genus, as represented by B. bidens of Borneo, differs from Xantharpyia in having only a single pair of upper incisors.
Cynopterus.[576]—Dentition: i ²⁄₂₋₁, c ¹⁄₁, p ³⁄₃, m ²⁄₂; total 32 or 30. Muzzle short, grooved like Pteropus in front; tail and fur generally as in Xantharpyia, but the former sometimes wholly absent. This genus, with seven species, is almost limited to the Oriental region. C. marginatus is very common in India, and extremely destructive to ripe fruit of every description. Dr. Dobson states that “he gave to a specimen of this Bat obtained at Calcutta a ripe banana, which, with the skin removed, weighed exactly 2 ounces; the animal immediately, as if famished with hunger, fell upon the fruit, seizing it between the thumbs and the index fingers, and took large mouthfuls out of it, opening the mouth to the fullest extent with extreme voracity. In the space of three hours the whole fruit was consumed. Next morning the Bat was killed, and found to weigh one ounce, or half the weight of the food eaten in three hours. Indeed the animal when eating seemed to be a kind of living mill, the food passing from it almost as fast as devoured, and apparently unaltered, eating being, as it were, performed only for the pleasure of eating.”
Harpyia.[577]—Dentition: i ¹⁄₀, c ¹⁄₁, p ²⁄₃, m ²⁄₂; total 24. Premaxillæ well developed and united in front; facial bones much elevated above the margin of the jaw, nostrils tubular (Fig. 303); body and limbs as in Cynopterus. Includes two species from the Austro-Malayan sub-region, readily recognised by the peculiar tubular and projecting nostrils, as shown in the accompanying woodcut.
Cephalotes.[578]—Dentition: i ¹⁄₁, c ¹⁄₁, p ²⁄₃, m ²⁄₃; total 28. Premaxillæ separate in front; nostrils simple; muzzle short; index finger without a claw; tail short. Includes one species, having the same distribution as Harpyia. The wing-membrane arises from the middle line of the back, to which it is attached by a longitudinal very thin process of the integument; the wings are quite naked, but the back covered by them is clothed with hair.
Pteralopex.[579]—External characters as in Pteropus; ears short and hairy; wings arising from the middle line of the back. Muzzle very short; plane of orbit directed more upwards than in Pteropus; orbit surrounded by bone; sagittal crest strongly developed. Teeth cuspidate; upper incisors with broad posterior ledges; upper canine short and thick, with a stout secondary cusp in the middle of the posterior border, and two smaller postero-internal basal cusps; cheek-teeth short and broad, with their anterior and posterior basal ledges so developed and the main cusps so nearly conical as to obliterate the longitudinal grooving of Pteropus. Lower incisors very disproportionate, the outer pair being nearly twenty times the bulk of the inner; lower canine stout, with a simple posterior basal ledge. Represented by P. atrata of the Solomon Islands. As already mentioned, Mr. Thomas regards the dentition of this genus as the most generalised type found in the suborder.
Subfamily =Carponycterinæ=.—Facial part of skull much produced; molars narrow, and scarcely raised above the gum; and the tongue exceedingly long, attenuated in the anterior third, and armed with long recurved papillæ near the tip.
Notopteris.[580]—Dentition: i ²⁄₁, c ¹⁄₁, p ²⁄₃, m ²⁄₂; total 28. Index finger without a claw; wings arising from the middle line of the back; tail long; first upper premolar long, with two roots. The single representative of the genus, N. macdonaldi, inhabits the Fiji Islands, Aneiteum Island, and New Guinea. It is at once distinguished from all other Bats of this family by the length of its tail, which is nearly as long as the forearm.
Eonycteris.[581]—Dentition: i ²⁄₂, c ¹⁄₁, p ³⁄₃, m ²⁄₃; total 34. First upper premolar small, with a single root. This genus is likewise represented by a single species (E. spelæa), from the Farm Caves, Moulmein, Burma, which has somewhat the appearance of Xantharpyia; but the absence of a claw to the index finger and the characteristic tongue and teeth at once distinguish it.
Carponycteris[582] and Melonycteris,[583] each with a single species, are closely allied; the index finger in both has a claw, and the number of the teeth is the same as in Eonycteris. Carponycteris minima is the smallest known species of the suborder, being much smaller than the common Noctule Bat of Europe, and its forearm scarcely longer than that of the Long-eared Bat. It is nearly as common in certain parts of India as Cynopterus marginatus (compared with which it is proportionally equally destructive to fruit), and extends eastward through the Malay Archipelago as far as New Ireland, where it is associated with Melonycteris melanops, distinguished from it by its larger size and the total absence of the tail.
Nesonycteris.[584]—Dentition: i ²⁄₁, c ¹⁄₁, p ³⁄₃, m ²⁄₃; total 32. Allied to Melonycteris, but distinguished by the absence of the inner pair of lower incisors, and of a claw to the index finger. Tail wanting. Represented by N. woodfordi, of the Solomon Islands.
Callinycteris.[585]—Dentition: i ²⁄₂, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 32. Allied to the preceding, but with a short tail; no claw to index. One species from Celebes.
Trygenycteris.[586]—Dentition: i ²⁄₂, c ¹⁄₁, p ³⁄₃, m ²⁄₃; total 34. No external tail; a claw on index. One species from West Africa.
Suborder MICROCHIROPTERA.
Insectivorous (rarely frugivorous or sanguivorous) Bats, of comparatively small size. Crowns of molars acutely cusped, marked by transverse grooves; bony palate narrowing abruptly, not continued backwards laterally behind the last molar; one rudimentary phalanx (rarely two phalanges or none) in the index finger, which is never terminated by a claw; outer and inner sides of ear-conch commencing inferiorly from separate points of origin; tail, when present, contained in the interfemoral membrane, or appearing upon its upper surface; stomach simple (except in the Desmodont Phyllostomatidæ); Spigelian lobe of the liver very large, and the caudate generally small. Inhabit the tropical and temperate regions of both hemispheres. The members of this suborder may be divided into two sections.
Section VESPERTILIONINA.
Tail contained within the interfemoral membrane; the middle pair of upper incisors never large, and separated from each other by a more or less wide space. Middle finger with two osseous phalanges only (except in Myxopoda aurita, Thyroptera tricolor, and Mystacops tuberculatus). First phalanx of the middle finger extended (in repose) in a line with the metacarpal bone.
Family RHINOLOPHIDÆ.
In all the species of this family the nasal appendages are highly developed, and surround the sides of the nasal apertures, which are situated in a depression on the upper surface of the muzzle; the ears are large and generally separate, without trace of a tragus; the premaxillæ are rudimentary, suspended from the nasal cartilages, and supporting a pair of very small incisors; the molars have acute W-shaped cusps; the skull is large, and the nasal bones which support the large nasal cutaneous appendages are much expanded vertically and laterally; in the females a pair of teat-like appendages are found in front of the pubis; and the tail is long and produced to the posterior margin of the interfemoral membrane. This family is found in the temperate and tropical parts of the eastern hemisphere.
From whatever point of view the Rhinolophidæ may be considered, they are evidently the most highly organised of insectivorous Bats. In them the osseous and cutaneous systems reach the most elaborate development. Compared with those of the present family the bones of the extremities and the flying-membranes of other Bats appear coarsely formed, and even their teeth seem less perfectly fitted to crush the hard bodies of insects. The very complicated nasal appendages, which evidently act as delicate organs of special perception, here reach their highest development, and the differences in their form afford valuable characters in the discrimination of the species, which resemble one another very closely in dentition and in the colour of the fur.
Subfamily =Rhinolophinæ=.—First toe with two, other toes with three, phalanges each; ilio-pectineal spine not connected by bone with the antero-inferior surface of the ilium.
Rhinolophus.[587]—Dentition: i ¹⁄₂, c ¹⁄₁, p ²⁄₃, m ³⁄₃; total 32. Nose-leaf (Fig. 304) with a central process behind and between the nasal orifices, posterior extremity lanceolate, antitragus large. Includes more than twenty species. R. luctus, in which the forearm has a length of 3 inches, is the largest species, inhabiting elevated hill tracts in India and Malayana; R. hipposiderus of Europe, extending into South England and Ireland, forearm 1·5 inches, is one of the smallest; and R. ferrum-equinum, with the forearm 2·3 inches in length, represents the average size of the species, which are mainly distinguished from one another by the form of the nose-leaf. The last-named species extends from England to Japan, and southward to the Cape of Good Hope. The genus is represented in the Himalaya by the closely allied R. tragatus, distinguished by having three vertical grooves on the lower lip, in place of the single groove found in R. ferrum-equinum. Rhinolophus is represented in the Upper Eocene Phosphorites of Central France by R. antiquus and R. dubius; the former appears to have the same dental formula as in the existing species, but differs slightly in the structure of some of the lower molars, so that it is separated generically by some writers under the name of Pseudorhinolophus. The face is also longer than in existing forms, and there are certain differences in the structure of the skull. Alastor, from the same deposits, differs from Rhinolophus by the extreme shortness of the nasal region. Palæonycteris, from the Lower Miocene of France, is said to be allied to Rhinolophus, but the premolars are ³⁄₃, and the limb bones are stated to resemble those of Molossus.
Subfamily =Hipposiderinæ=.—Toes equal, of two phalanges each; ilio-pectineal spine united by a bony isthmus with a process derived from the antero-inferior surface of the ilium.
Hipposiderus.[588]—Dentition: i ¹⁄₂, c ¹⁄₁, p ²⁻¹⁄₂, m ³⁄₃; total 30 or 28. Tail well developed. This genus, of which more than twenty species have been described, differs from Rhinolophus in the form of the nose-leaf, which is not lanceolate behind and is unprovided with a central process covering the nostrils. The largest species, H. armiger, appears to be the most northerly, having been taken at Amoy in China, and in the Himalaya at an elevation of 5,500 feet. Many of the species are provided with a peculiar frontal sac behind the nose-leaf, rudimentary in females (Fig. 305), which the animal can evert at pleasure; the sides of this sac secrete a waxy substance, and its extremity supports a pencil of straight hairs.
Anthops.[589]—Like Hipposiderus, but with the tail rudimentary, consisting merely of three or four vertebræ hidden in the base of the interfemoral membrane. Nose-leaf very complicated, its upright transverse portion emarginate above, and the projections rounded and hollowed behind, and their substance quite thin. Premolars ²⁄₂. Represented by A. ornatus of the Solomon Islands.
Mr. O. Thomas, the describer of this Bat, remarks that it is evidently more nearly allied to the preceding than to the succeeding genera, although it agrees with Cœlops in the rudimentary tail.
Rhinonycteris[590] and Triænops.[591]—These are two allied genera with well-developed tails; the former being represented by R. aurantia from Australia, and the latter by T. persicus from Persia and Eastern Africa. Triænops (Fig. 306) is characterised by the remarkable form of its nasal appendages and ears, and the presence of a peculiar osseous projection from the proximal extremity of the second phalanx of the fourth finger.
Cœlops.[592]—This genus is known only by a single species, C. frithi, from the Bengal Sunderbans, Java, and Siam (in the roof of the great pagoda at Laos); and is distinguished, not only by the form of its nose-leaf, but also by the great length of the metacarpal of the index finger, as well as by the shortness of the calcar and interfemoral membrane and the rudimental tail.
Family NYCTERIDÆ.
This small family, including only two genera of Bats of peculiar aspect, limited to the tropical and subtropical parts of the eastern hemisphere, is distinguished from the Rhinolophidæ by the presence of a distinct tragus to the ear, and by the premaxillæ being cartilaginous or small and separated from one another in front by a distinct space.
Megaderma.[593]—Dentition: i ⁰⁄₂, c ¹⁄₁, p ²⁻¹⁄₂, m ³⁄₃; total 28 or 26. This genus, which is represented by five species, is readily recognised by the absence of upper incisors, the cylindrical narrow muzzle surmounted by an erect naked cutaneous nose-leaf, the base of which conceals the nasal orifices, by the immense connate ears with large bifid tragi, and by the great extent of the interfemoral membrane, in the base of which the very short tail is concealed. M. gigas (Fig. 307), from Central Queensland (length of forearm 4·2 inches), is not only the largest species of the genus but also of the suborder. M. lyra, common in India (forearm 2·7 inches), has been caught in the act of sucking the blood, while flying, from a small species of Vesperugo, which it afterwards devoured, so that it is probable that the Bats of this genus do not confine themselves to insect prey alone, but also feed, when they can, upon the smaller species of Bats and other small mammals.
The Oriental M. spasma and M. lyra differ from the Ethiopian M. cor and M. frons in having two upper premolars instead of one, and also in the shape of the frontals and nasals.
Nycteris.[594]—Dentition: i ²⁄₃, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 32. This genus, of which there are seven species, differs so much from Megaderma that it may be considered the type of a separate subfamily. As in that genus, the frontal bones are deeply hollowed out and expanded laterally, the muzzle presents a similar cylindrical form, and the lower jaw also projects, but the single elevated nose-leaf is absent, and instead of it the face is marked by a deep, longitudinal, sharp-edged groove extending from the nostrils (which are on the upper surface of the muzzle, near its extremity) to the low band connecting the bases of the large ears, the sides of this depression being margined as far back as the eyes by small horizontal cutaneous appendages. All the species resemble one another closely, and are mainly distinguished by the form of the tragus and the size and relative position of the second lower premolar. With the exception of N. javanica, they are all limited to the Ethiopian region.
Family VESPERTILIONIDÆ.
Nostrils opening by simple crescentic or circular apertures at the extremity of the muzzle, not surrounded by distinct foliaceous cutaneous appendages; premaxillæ small, lateral, and separated by a wide space in front; tragus distinct. In addition to these characters, it may be observed that the skull is of moderate size, the nasal and frontal bones not being much extended laterally or vertically, nor furrowed by deep depressions. The number of incisors varies from ²⁄₃ to ¹⁄₃, rarely (in Antrozous only) ¹⁄₂, premolars ³⁄₃, or ²⁄₂, or ¹⁄₂, rarely (in Vesperugo noctivagans of North America) ²⁄₃; the upper incisors are small, separated by a wide space in the middle line, and placed in pairs or singly near the canine; the molars are well-developed, with acute W-shaped cusps.
This family, which may be regarded as occupying a central position in the suborder, includes the common simple-faced Bats of all countries, of which the well-known Pipistrelle and the Whiskered Bat (Vespertilio mystacinus) may be taken as familiar types, and its species number more than 150, or considerably more than one-third the total number of the known species of the entire order. The various genera may be conveniently grouped into the Plecotine, Vespertilionine, Miniopterine, and Thyropterine divisions.
In the Plecotine division, of which the common Long-eared Bat (Plecotus auritus) is the type, the crown of the head is but slightly raised above the face-line, the outermost upper incisor is close to the canine, and the nostrils are margined behind by grooves on the upper surface of the muzzle, or by rudimentary nose-leaves; the ears also are generally very large and united.
Plecotus.[595]—Dentition: i ²⁄₃, c ¹⁄₁, p ²⁄₃, m ³⁄₃; total 36. Outer margin of ear-conch ending abruptly near the angle of the mouth, the inner margin with a more or less prominent rounded projection directed inwardly above the base; tragus very large, tapering upwards, with a lobe at the base of its outer margin, rounded, and placed half horizontally. This genus is represented by the European Long-eared Bat (P. auritus), and P. macrotis, restricted to North America. The latter is distinguished by the great size of the glandular prominences of the sides of the muzzle, which meet in the centre above and behind the nostrils. P. auritus extends over the greater part of the Palæarctic region, occurring in Ireland in the west and the Himalaya in the east.
Synotus.[596]—Dentition: i ²⁄₃, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 34. This genus is distinguished from the preceding by the loss of one lower premolar and by the outer margin of the ear being carried forwards above the mouth and in front of the eye; it includes the European Barbastelle Bat (S. barbastellus) and S. darjilingensis from the Himalaya.
Otonycteris.[597]—Dentition: i ¹⁄₃, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 30. The reduction in the number of upper incisors readily characterises this genus, which appears to connect the typical representatives of the section, through Scotophilus, with the Vespertilionine division. It is represented by a single species, O. hemprichi, from North Africa and the Himalaya.
Nyctophilus.[598]—Dentition: i ¹⁄₃, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 30. This and the following genera are distinguished from all the preceding by the presence of a rudimentary nose-leaf. The present genus contains N. timoriensis of the Australian region, and N. microtis of New Guinea.
Antrozous.[599]—Dentition: i ¹⁄₂, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 28. Readily distinguished from the other members of the whole family by having but two lower incisors, and from the other species of the section by the separate ears. The single species, A. pallidus, inhabits California.
The Vespertilionine division includes some nine-tenths of all the representatives of the family. They are distinguished from the preceding section by the simple nostrils, opening by crescentic or circular apertures at the extremity of the muzzle, the generally small size of the ears, and the absence of grooves on the forehead.
Vesperugo.[600]—Dentition: i ²⁻¹⁄₃, c ¹⁄₁, p ²⁻¹⁄₂₋₃, m ³⁄₃; total 34, 30, or 36. This large genus comprises about one-third of the section, and is divided into groups or subgenera, according to the number of premolars and incisors; the latter varying from ²⁄₃ to ¹⁄₃ in the subgenera Scotozous and Rhogeëssa, and the premolars from ²⁄₂ to ¹⁄₂ (in the subgenus Lasionycteris ²⁄₃). The Bats of this genus are generally easily distinguished by their comparatively thickly formed bodies, flat broad heads and obtuse muzzles, short, broad, and triangular obtusely-pointed ears, obtuse and usually slightly incurved tragus, short legs, and by the presence in most species of a well-developed post-calcaral lobule. This lobule (which is supported by a cartilaginous process derived from the calcar) may act as a kind of adhesive disc in securing the animal’s grasp when climbing over smooth surfaces. Vesperugo probably contains the greatest number of individuals among the genera of Chiroptera, and, with the exception of Vespertilio, its species have also the widest geographical range, being almost cosmopolitan; and one of the species, the well-known Serotine (V. [Vesperus] serotinus) is remarkable as the only species of Bat known to inhabit both the Old and the New World; one (V. borealis) has been found close to the limits of the Arctic circle, and another (V. magellanicus) inhabits the cold and desolate shores of the Straits of Magellan, being doubtless the Bat referred to by Mr. Darwin in the Naturalist’s Voyage. The Common Pipistrelle (V. pipistrellus), ranging over the greater part of the Palæarctic region, is the best known species.
Chalinolobus.[601]—This genus agrees with Vesperugo in the dental formula, but is readily distinguished by the presence of a well-defined lobe projecting near the angle of the mouth from the lower lip, and by the unicuspidate first upper incisor. The species fall into two subgenera—Chalinolobus proper, with p ²⁄₂, represented by C. morio from New Zealand, Tasmania, and Australia, and three other species from Australia; and Glauconycteris, with p ¹⁄₂, limited to Southern and Equatorial Africa, and known by C. argentatus and two other species, the Bats of this subgenus being especially remarkable for their peculiarly thin membranes, traversed by very distinct reticulations and parallel lines.
Scotophilus.[602]—Dentition: i ¹⁄₃, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 30. This genus comprises a comparatively small number of species nearly allied to Vesperugo, and some of which approach so closely to the aberrant types of the latter ranged under the subgenus Scotozous, as to render the definition of the present genus almost impossible.[603] The species are restricted to the tropical and subtropical regions of the eastern hemisphere, though widely distributed within these limits. The more typical species are distinguished especially by the single pair of unicuspidate upper incisors separated by a wide space and placed close to the canines, by the small transverse first lower premolar squeezed in between the canine and second premolar, and, generally, by their conical nearly naked muzzles and remarkably thick leathery membranes. S. kuhli is probably the commonest species of Bat in India, and appears often on the wing even before the sun has touched the horizon, especially when the white-ants are swarming, feeding eagerly upon them as they rise in the air. S. gigas, from Equatorial Africa, with the forearm measuring 3·4 inches, is by far the largest species. S. albofuscus, from the Gambia, which is readily distinguished from the other species by its white wings, is an aberrant form, in which the lower premolars are long and not crowded together, and thereby so closely resembles Vesperugo (Scotozous) dormeri as to render it almost impossible to distinguish Scotophilus and Vesperugo. The figured species is from India.
Nycticejus.[604]—This genus, with the same dental formula as Scotophilus, is distinguished by the first lower premolar not being squeezed in between the adjoining teeth, and by the comparatively much greater size of the last upper molar. It includes only the common North American N. humeralis (crepuscularis), a small Bat scarcely larger than the Pipistrelle. It seems, however, as pointed out by Mr. O. Thomas, that the discovery of Scotophilus albofuscus renders the generic distinctness of Nycticejus no longer tenable, and that the species should be known as Scotophilus humeralis.
Atalapha.[605]—Dentition: i ¹⁄₃, c ¹⁄₁, p ²⁻¹⁄₂, m ³⁄₃; total 32 or 30. The five species of this genus, which are confined to the New World, are generally characterised by the interfemoral membrane being more or less covered with hair (in the two commonest species, A. noveboracensis and A. cinerea, wholly covered), and by the peculiar form of the tragus, which is expanded above and abruptly curved inwards. These species have two upper premolars, of which the first is extremely small and quite internal to the tooth-row.
Harpyiocephalus.[606]—Dentition: i ²⁄₃, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 34. This genus includes some eight species of small Bats distinguished by their prominent tube-like nostrils and hairy interfemoral membrane. H. suillus, from Java and neighbouring islands, is the best-known species, and another closely allied (H. hilgendorfi)has been described by Professor Peters from Japan. The remaining six species are known only from the Himalaya and Tibet. All appear to be restricted to the hill tracts of the countries in which they are found.
Vespertilio.[607]—Dentition: i ²⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 38. Next to Vesperugo, this genus includes by far the largest number of species, amounting to over forty; it has, however, rather a wider geographical distribution in both hemispheres, one species at least being recorded from the Navigators’ Islands. The species are easily recognised by the peculiar character of the upper incisors, the crowns of which diverge from each other; by the large number of premolars, of which the second upper one is always very small; and by the oval elongated ear and narrow attenuated tragus. In the British Isles this genus is represented by four species, viz. Bechstein’s Bat (V. bechsteini); the Reddish-Gray Bat (V. nattereri), of very local occurrence; Daubenton’s Bat (V. daubentoni); and the Whiskered Bat (V. mystacinus).
Cerivoula.[608]—This genus, which has the same dental formula as Vespertilio, is distinguished by the parallel upper incisors, and the comparatively large size of the second upper premolar. Some ten species have been described from the Ethiopian and Oriental regions, of which C. picta, from India and the Indo-Malayan sub-region, is the best-known, being well characterised by its brilliantly coloured orange fur and conspicuously marked membranes, which are variegated with orange and black. This genus includes the most delicately formed and most truly insectivorous, tropical, forest-haunting Bats, which appear to stand as regards the species of Vespertilio in a position similar to that occupied by Chalinolobus with respect to Vesperugo.
The Miniopterine division includes only two genera, and is characterised by the great elevation of the crown of the head above the facial line, and also by the upper incisors being separated from the canine and also in the middle line.
Natalus.[609]—This genus, while having the divisional characters mentioned above, agrees in the dental formula and its general external form with Cerivoula, from which it is distinguished by the short triangular tragus. It includes three species, restricted to South and Central America and the West Indies; the head of N. micropus being shown in Fig. 310.
Miniopterus.[610]—Dentition: i ²⁄₃, c ¹⁄₁, p ²⁄₃, m ³⁄₃; total 36. In addition to the difference in the number of the teeth, this genus is distinguished by the shortness of the first phalanx of the middle finger and the great length of the tail, which is wholly contained within the interfemoral membrane; it includes four species, restricted to the eastern hemisphere. Of these the best-known, M. schreibersi, is very widely distributed, being found almost everywhere throughout the tropical and warmer temperate regions of the eastern hemisphere; specimens from Germany, Madagascar, Japan, and Australia differing in no appreciable respect from one another.
The last or Thyropterine division, which likewise comprises only two genera, is characterised by the presence of an additional osseous phalanx in the middle finger and an equal number of phalanges in the toes, and also by peculiar accessory clinging organs attached to the extremities.
Thyroptera.[611]—Dentition: i ²⁄₃, c ¹⁄₁, p ³⁄₃, m ³⁄₃; total 38. In the single species T. tricolor of Brazil the clinging organs have the appearance of small, circular, pedunculated, hollow discs (Fig. 311), resembling in miniature the sucking cups of cuttle-fishes, and are attached to the inferior surfaces of the thumbs and soles of the feet. With these the animal is enabled to maintain its hold when creeping over smooth vertical surfaces.
Myxopoda.[612]—The second genus is likewise represented only by a single species—M. aurita of Madagascar—and is distinguished from the preceding by the characters of the teeth and the form of the ears. The whole inferior surface of the pollex supports a large sessile horse-shoe-shaped adhesive pad, with the circular margin directed forwards and notched along its edge, and a smaller pad occupies part of the sole of the foot.
Fossil Vespertilionidæ.—It is not improbable that Vesperugo is represented in the Upper Eocene of the Paris basin by V. parisiensis, which appears to be allied to V. serotina, although it has been regarded by some writers as generically distinct, under the name of Nyctitherium. Vesperugo (Nyctitherium) also occurs in the Bridger Eocene of the United States; Nyctilestes from the same deposits being an allied extinct genus. A number of European Miocene species have been referred to Vespertilio, but the term in these cases must be used in a somewhat wide sense. Vespertiliavus, of the Phosphorites of Central France, differs from Vespertilio in the proportions of its premolars.
Section EMBALLONURINA.
Tail perforating the interfemoral membrane and appearing on its upper surface, or produced considerably beyond the truncated membrane; the middle pair of upper incisors generally large and close together.
Family EMBALLONURIDÆ.
First phalanx of the middle finger folded (in repose) on the dorsal surface of the metacarpal bone (except in Noctilio and Mystacops). Nostrils opening by simple circular or valvular apertures at the extremity of the muzzle, not surrounded or margined by foliaceous cutaneous appendages; tragus distinct.
The Emballonuridæ are generally easily distinguished by the peculiar form of the muzzle, which is obliquely truncated, the nostrils projecting more or less in front beyond the lower lip; by the first phalanx of the middle finger being folded in repose forwards on the upper surface of the metacarpal bone; by the tail, which either perforates the interfemoral membrane or is produced far beyond it; and by the upper incisors, which are generally a single pair separated from the canine and also in the middle line. The family is cosmopolitan like the Vespertilionidæ, but rarely extends north or south of the thirtieth parallel of latitude.
Subfamily =Emballonurinæ=.—Tail slender, perforating the interfemoral membrane, and appearing upon its upper surface, or terminating in it; legs long, fibula very slender; upper incisors weak.
In the Furipterine division the tail terminates in the interfemoral membrane; the crown of the head is greatly elevated above the face-line; the thumb and first phalanx of the middle finger are very short; and the dentition is i ²⁄₃, c ¹⁄₁, p ²⁄₃, m ³⁄₃; total 38.
Represented by two genera, Furipterus[613] and Amorphochilus,[614] each including one species of peculiar aspect; the latter distinguished from the former by the widely separated nostrils and the great extension backwards of the bony palate. Habitat South America.
In the typical or Emballonurine division part of the tail is included in the basal half of the interfemoral membrane, the remaining part passing through and appearing upon its upper surface; the crown of the head is slightly elevated; the pollex and first phalanx of the middle finger are moderately long; and the number of the premolars is always ²⁄₂.
Emballonura.[615]—Incisors ²⁄₃. Extremity of the muzzle more or less produced beyond the lower lip, forehead flat. Contains some five species, inhabiting islands from Madagascar through the Malay Archipelago to the Navigators’ Islands.
Coleüra.[616]—Incisors ¹⁄₃. Extremity of the muzzle broad, forehead concave. Has two species from East Africa and the Seychelles Islands.
Rhynchonycteris.[617]—This genus is distinguished from Coleüra by the much-produced extremity of the muzzle. The single species, R. naso, from Central and South America, is very common in the vicinity of streams throughout the tropical parts of these countries; it is usually found during the day resting on the vertical faces of rocks, or on the trunks of trees growing over the water, and, owing to the peculiar grayish colour of the fur covering the body and growing in small tufts from the antebrachial membrane, so as to counterfeit the weathered surfaces of rocks and the bark of trees, easily escapes notice. As the shades of evening approach it appears early on the wing, flying close to the surface of the water, and seizing the minute insects that hover over it.
Saccopteryx.[618]—Incisors ¹⁄₃. Antebrachial membrane with a pouch opening on its upper surface. This genus contains six species from Central and South America. In the adult males a valvular longitudinal opening is found on the upper surface of the membrane, varying in position in different species. This opening leads into a small pouch (in some species large enough to hold a pea), the interior of which is lined with a glandular membrane secreting an unctuous substance of a reddish colour with a strong ammoniacal odour. The presence of this sac only in males indicates that it is a secondary sexual character analogous to the shoulder-pouches of Epomophorus and the frontal sacs of Hipposiderus. It is quite rudimentary in the females.
Taphozous.[619]—Incisors ¹⁄₂; upper pair deciduous. This genus, represented by some ten species, inhabiting the tropical and subtropical parts of all the eastern hemisphere except Polynesia, forms the second group of this division, distinguished by the cartilaginous premaxillaries, deciduous upper incisors, and the presence of only two lower incisors. Most of the species have a peculiar glandular sac (Fig. 313) placed between the angles of the lower jaw. This is a sexual character, for, while always more developed in males than in females, in some species, although distinct in the male, it is quite absent in the female. An open gular sac is wanting in both sexes in T. melanopogon, but about its usual position the openings of small pores may be seen, the secretion exuding from which probably causes the hairs to grow very long, forming the black beard found in many male specimens of this species.
In the Diclidurine division there is but a single genus, represented by two species.
Diclidurus.[620]—Dentition: i ¹⁄₃, c ¹⁄₁, p ²⁄₂, m ³⁄₃; total 32. Both species are from the Neotropical region, the typical D. albus ranging as far north as Central America. This Bat resembles the species of Taphozous in the form of the head and ears, but, besides other characters, differs from all other Bats in possessing a peculiar pouch, opening on the centre of the inferior surface of the interfemoral membrane; the extremity of the tail enters this, and perforates its fundus.
The Noctilionine division is likewise represented only by a single genus, with two species. This genus connects the present with the following family, possessing characters common to both, but also so many remarkable special peculiarities as almost to warrant the formation of a separate family for its reception.
Noctilio.[621]—Dentition: i ²⁄₁, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 28. The two species N. leporinus and N. albiventer inhabit Central and South America. The typical N. leporinus is a Bat of very curious aspect, with strangely folded lips, erect cutaneous processes on the chin, and enormous feet and claws. The first upper incisors are close together, and so large as to conceal the small outer ones, while in the lower jaw there is one pair of small incisors. This apparent resemblance to a Rodent actually led Linnæus to remove this species from the Bats and place it in the Rodents. This Bat is remarkable for feeding on fish—a circumstance which has only recently been fully authenticated.
The remaining genus of this subfamily is regarded as representing another division, which may be known as the Rhinopomatine division.
Rhinopoma.[622]—This genus, represented by the single species R. microphyllum, might also be elevated to the rank of a family, for it is difficult to determine its exact affinities, a kind of cross relationship attaching it to the Nycteridæ on the one hand and to this family, in which it is here placed provisionally, on the other. This species, distinguished from all other Microchiroptera as well by the presence of two phalanges in the index finger as by its remarkably long and slender tail projecting far beyond the narrow interfemoral membrane, inhabits the subterranean tombs in Egypt and deserted buildings generally from North-East Africa to Burma.
Subfamily =Molossinæ=.—Tail thick, produced far beyond the posterior margin of the interfemoral membrane (except in Mystacops); legs short and strong, with well-developed fibula; upper incisors strong. This subfamily includes all the species of Emballonuridæ with short and strong legs and broad feet (whereof the first toe, and in most species the fifth also, is much thicker than the others, and furnished with long curved hairs), well-developed callosities at the base of the thumbs, and a single pair of large upper incisors occupying the centre of the space between the canines. In all the species the feet are free from the wing-membrane, which folds up perfectly under the forearm and legs; the interfemoral membrane is retractile, being movable backwards and forwards along the tail, and this power of varying its superficial extent must confer upon these Bats great dexterity in quickly changing the direction of their flight, as when obliged to double in pursuing their swift insect prey, which their extremely expansible lips evidently enable them to secure with ease. Like the preceding subfamily, the genera may be arranged in divisions, of which there are two.
The Molossine division is characterised by the production of the tail beyond the posterior margin of the interfemoral membrane; it includes three genera.
Chiromeles.[623]—Dentition: i ¹⁄₁, c ¹⁄₁, p ¹⁄₂, m ³⁄₃; total 26. Hallux much larger than the other toes and separable from them, ears separate. This genus is represented by a single species, C. torquatus, of large size (forearm 3·1 inches) and peculiar aspect, inhabiting the Indo-Malayan sub-region. This Bat is nearly naked, a collar only of thinly spread hairs half surrounding the neck; and is further remarkable for its enormous throat-sac and curious nursing-pouches. The former consists of a great semicircular fold of skin forming a deep pouch round the neck beneath, and concealing the orifices of large subcutaneous pectoral glands, which discharge an oily fluid of insufferably offensive smell. The nursing-pouch is formed on each side by an extension of a fold of skin from the side of the body to the inferior surfaces of the humerus and femur. In the anterior part of this pouch the mammæ are placed.
Molossus.[624]—Dentition: i ¹⁄₁₋₂, c ¹⁄₁, p ¹⁻²⁄₁, m ³⁄₃; total 24 or 28. Upper incisors close together in the middle line. There are some ten species, restricted to the tropical and subtropical regions of the New World. The woodcut of the head of M. glaucinus (Fig. 315) exhibits the general physiognomy of the Bats of this genus. M. obscurus, a small species, is very common in tropical America. It inhabits the hollow trunks of palms and other trees, and also the roofs of houses. The males and females live apart (as, indeed, appears to be the case in most, if not in all, species of Bats). In the hollow trunk of a palm two colonies were discovered, one consisting of from 150 to 200 individuals, exclusively males, while the other was composed almost entirely of females.
Nyctinomus.[625]—Dentition: i ¹⁄₃₋₂, c ¹⁄₁, p ²⁻¹⁄₂, m ³⁄₃; total 32 or 28. Upper incisors separated in the middle line. The genus contains about twenty-five species, inhabiting the tropical and subtropical parts of both hemispheres. The lips of the Bats of this genus are even more expansible than in Molossus, in many of the species (as in the woodcut of the head of N. macrotis, Fig. 316) showing vertical wrinkles. N. tæniotis, one of the largest species, alone extends into Europe, and has been taken as far north as Switzerland. N. johorensis, from the Malay Peninsula, is remarkable from the extraordinary form of its ears. N. brasiliensis is nearly as common as Molossus obscurus in tropical America, and extends farther north (California) and south than that species.
In the Mystacopine division the tail perforates the interfemoral membrane and appears upon the upper surface.
Mystacops.[626]—This genus includes only M. tuberculatus of New Zealand, where, together with Chalinolobus tumorio, it represents the whole indigenous mammalian fauna of the islands. There are three distinct phalanges in the middle finger; the greater part of the wing-membrane is exceedingly thin, but a narrow portion along the forearm, the sides of the body, and the legs is remarkably thick and leathery; beneath this thickened portion the wings are folded. With the wings thus encased, this species is the most quadrupedal of Bats. Other peculiarities of structure are found in the remarkable form of the claws of the thumbs and toes, which have each a small talon projecting from its concave surface near the base, also in the sole of the foot and inferior surface of the leg, as shown in Fig. 317. The plantar surface, including the toes, is covered with soft and very lax integument deeply wrinkled, and each toe is marked by a central longitudinal groove with short grooves at right angles to it. The lax wrinkled integument is continued along the inferior flattened surface of the ankle and leg. These peculiarities appear to be related to climbing habits in the species.
Fossil Emballonuridæ.—In the cavern-deposits of Madras remains of the existing Taphozous saccolæmus are not uncommon; while in the corresponding beds of Brazil bones of a Molossus, probably referable to M. temmincki, now inhabiting the same region, are met with. It has been suggested that remains from the Upper Eocene Phosphorites of Central France may indicate the existence of the genus Taphozous at that early epoch.
Family PHYLLOSTOMATIDÆ.
Middle finger with three well-developed bony phalanges; first phalanx of the middle finger short; nostrils in the front part of the cutaneous nasal appendages, or opening by simple apertures at the extremity of the muzzle; chin with warts or erect cutaneous ridges; premaxillæ well developed, united in front.
The members of this family are readily distinguished by the third phalanx in the middle finger, associated either with distinct cutaneous nasal appendages, or with well-developed first upper incisors, or with both. Unlike the Rhinolophidæ, their eyes are generally large; and the tragus is well developed, maintaining almost the same form throughout the species, however much the other parts of the body may vary. The fur is of a dull colour, and the face and back (in the Stenodermatine division especially) are often marked with white streaks, as in the Pteropodidæ, of which these Bats take the place in the western hemisphere. A few species, probably all those with the tail and interfemoral membrane well developed, feed principally on insects, while the greater number of the species of the Vampirine and Glossophagine divisions appear to live on a mixed diet of insects and fruits; and the Desmodontine division, of which two species only are known, are true blood-suckers, and have their teeth and intestinal tract specially modified in accordance with their habits. The family is restricted to the tropical and subtropical parts of Central and South America.
Subfamily =Chilonycteriinæ=.—Nostrils opening by simple apertures at the extremity of the muzzle in front, not margined by a distinct nose-leaf; chin with expanded leaf-like appendages. It includes two genera.
Chilonycteris.[627]—Dentition: i ²⁄₂, c ¹⁄₁, p ²⁄₃, m ³⁄₃; total 34. The crown of the head is moderately elevated above the facial line, and the basicranial axis is almost in the same plane as the facial. There are about half a dozen species.
Mormops.[628]—The two species of this genus are distinguished from Chilonycteris by the great elevation of the crown of the head above the line of the face, as well as by the basicranial plane being nearly at right angles to the facial. Both species are noticeable for their peculiar physiognomy, as is shown in the accompanying woodcut (Fig. 318).
Subfamily =Phyllostomatinæ=.—Nostrils opening on the upper surface of the muzzle, the nasal apertures more or less surrounded or margined by well-developed cutaneous appendages, forming a distinct nose-leaf; chin with warts. The numerous genera, most of which can only be mentioned here by name, may be arranged under four divisions.
In the first or Vampirine division the muzzle is long and narrow in front; the distance between the eyes is generally less than, rarely equal to, that from the eye to the extremity of the muzzle; the nose-leaf is well developed, horse-shoe shaped in front, and lanceolate behind; interfemoral membrane well developed; tail generally distinct, rarely absent; inner margin of the lips not fringed. The dentition is: i ²⁄₂₋₁, c ¹⁄₁, p ²⁄₂₋₃, m ³⁄₃; total 32. The cusps of the upper molars are usually well developed, and arranged in a W. Nearly all the species of this division appear to be insectivorous, so that the name applied to them must not be considered as having any relation to their habits. Vampyrus spectrum, a large Bat inhabiting Brazil, of forbidding aspect, which was long considered by naturalists to be sanguivorous in its habits, and named accordingly by Geoffroy, has been shown by the observations of modern travellers to be mainly frugivorous, and is considered by the inhabitants of the countries in which it is found to be perfectly harmless. It is the largest Bat in America, the length of the forearm being 4·2 inches. Otopterus waterhousei appears to prey occasionally on small species of Bats, like Megaderma lyra of the eastern hemisphere, which it resembles in many respects.
Lonchorhina,[629] Otopterus,[630] and Dolichophyllum.[631]—These three genera are characterised by the tail continuing to the hinder margin of the interfemoral membrane. Lonchorhina is represented by the single species L. aurita, in which the nose-leaf is much elongated, and the ear-conch and tragus are unusually large.
Vampyrus,[632] etc.—In all the remaining genera of this division the tail perforates the interfemoral membrane, so as to appear upon its upper surface. These genera are Vampyrus, Lophostoma, Micronycteris,[633] Trachyops, Phylloderma, Phyllostoma, Anthorhina,[634] Mimon, Hemiderma[635] and Rhinophylla; all, with the exception of the last, being distinguished from one another chiefly by the form of the skull and the presence or absence of the second lower premolar. Trachyops, Phylloderma, and the three last-named genera are each represented by a single species. Phyllostoma hastatum, in which the forearm has a length of 3·2 inches, and next in point of size to Vampyrus spectrum, is a well-known species in South America; P. elongatum (Fig. 319) differs in its smaller size and much larger nose-leaf. Hemiderma brevicauda is a small species, which forms a connecting link between this and the next division. Rhinophylla pumilio, the smallest known species of the family, is further distinguished by the narrowness of its molars, which do not form W-shaped cusps, and by the very small size of the last upper molar; characters connecting it with the Stenodermatine division.
In the second or Glossophagine division of the subfamily the muzzle is long and narrow; the tongue remarkably long and extensible, much attenuated towards the tip, and beset with very long filiform recurved papillæ; lower lip with a wide groove above, and in front margined by small warts; nose-leaf small; tail short or absent. Dentition: i ¹⁄₁, c ²⁄₂, p ²⁻³⁄₃₋₂, m ²⁄₃₋₂; teeth very narrow; molars with narrow W-shaped cusps, sometimes indistinct or absent; lower incisors very small or deciduous.
The ten species included in this division are arranged under seven genera,[636] distinguished principally by differences in the form and number of the teeth and the presence or absence of the zygomatic arch. The form and position of the upper incisors are extremely variable. In Glossophaga and Phyllonycteris the upper incisors form, as in the Vampyrine division, a continuous row between the canines; in Monophylla and Leptonycteris[637] they are separated into pairs by a narrow interval in front; while in Lonchoglossa, Glossonycteris, and Chœronycteris they are widely separated and placed in pairs near the canines. In the first four genera the lower incisors are present (at least up to a certain age), while in the last three they are deciduous even in youth. The zygomatic arch is wanting in Phyllonycteris, Glossonycteris, and Chœronycteris.
The typical species is Glossophaga soricina, which so closely resembles Hemiderma brevicauda, both in external form and dentition, that it has frequently been confounded with it. Its long fimbriated tongue, which it possesses in common with other species of the division, led Spix to describe it as a blood-sucker, believing that this organ was used to increase the flow of blood. This view is, however, without foundation, and from later observations it is evident that the peculiarly shaped tongue is used by the animal to lick out the pulpy contents of fruits having hard rinds. The food of the species of this division appears to consist of both fruit and insects, and the long tongue may also be used for extracting the latter from the deep corollæ of certain flowers. This type of tongue is shown in the woodcut of the head of Chœronycteris (Fig. 320); and it is paralleled among the Megachiroptera by the Carponycteriine Pteropodidæ.
The Stenodermatine division is characterised by the muzzle being very short and generally broad in front, the distance between the eyes nearly always exceeding (rarely equal to) that from the eye to the extremity of the muzzle; nose-leaf short, horse-shoe shaped in front, lanceolate behind (except in Brachyphylla and Centurio); interfemoral membrane always concave behind; tail none; inner margin of the lips fringed with conical papillæ. Dentition: i ²⁄₂₋₁, p ²⁄₂, m ³⁻²⁄₃₋₂; the number of the molars being either ³⁄₃, ²⁄₃, or ²⁄₂ in different species; premolars and molars very broad (except in Sturnira), the latter with concave or flat crowns margined externally by raised cutting-edges. Although the members of this division are usually distinguished from those of the Vampirine division by the peculiar shortness and breadth of the muzzle and the form of the molars, yet certain species of the latter closely resemble those of the former in external appearance, agreeing almost absolutely in the form of the nose-leaf, of the ears and tragus, and of the warts on the chin. These resemblances indicate that, while the form of the teeth and jaws has become modified to suit the nature of the food, the external characters, being but slightly affected by this cause, have remained much the same. The food of these Bats appears to be wholly or in great part fruit. The twenty species have been grouped into nine genera, distinguished by the form of the skull and teeth. Artibeus, with six species, includes the well-known frugivorous Bat, A. perspicillatus. Waterton believed that A. planirostris, a common Bat in British Guiana, usually found in the roofs of houses, and now known to be frugivorous, was the true blood-sucking Vampire. Stenoderma achradophilum, found in Jamaica and Cuba, associated with Artibeus perspicillatus, from which it is scarcely distinguishable externally except by its much smaller size, differs altogether in the absence of the horizontal plate of the palatal bones. Sturnira lilium, while agreeing with the above in the form of the nose-leaf and ears, differs from all the species of the family in its longitudinally-grooved molars, which resemble those of the Pteropodidæ more closely than those of any other Bats; and the presence of tufts of long differently coloured hairs over glands in the sides of the neck shows another common character still more remarkable, which can scarcely be considered the result of adaptive change. Centurio senex is the type of a genus distinguished from Stenoderma and other genera of this division by the absence of a distinct nose-leaf; its facial aspect, as shown in Fig. 321, is altogether bizarre.
In the last or Desmodont division the muzzle is conical and short; there is a distinct nose-leaf; the interfemoral membrane is very short; and the tail is wanting. Dentition: i ¹⁄₂, c ¹⁄₁, p ²⁄₃, m ¹⁻⁰⁄₁₋₀; total 24 or 20. Upper incisors very large, trenchant, occupying the whole space between the canines; premolars very narrow, with sharp-edged longitudinal crowns; molars rudimentary or wanting; stomach greatly elongated, intestiniform. There are only two genera, the single species of each of which are the true blood-sucking Vampires. They appear to be confined chiefly to the forest-clad parts, and their attacks on men and other warm-blooded animals were noticed by some of the earliest writers. Thus Peter Martyr (Anghiera), who wrote soon after the conquest of South America, says that in the Isthmus of Darien there were Bats which sucked the blood of men and cattle when asleep to such a degree as to kill them. Condamine, a writer of the eighteenth century, remarks that at Borja (Ecuador) and in other places they had entirely destroyed the cattle introduced by the missionaries. Sir Schomburgk relates that at Wicki, on the river Berbice, no fowls could be kept on account of the ravages of these creatures, which attacked their combs, causing them to appear white from loss of blood. Although these Bats were known thus early to Europeans, the species to which they belonged were not determined until about sixty years ago, several of the large frugivorous species having been wrongly set down as blood-suckers and named accordingly; and it fell to the lot of Darwin to determine at least one of the blood-sucking species, the following being his account of the circumstances under which the discovery of the sanguivorous habits of Desmodus rufus was made: “The Vampire Bat is often the cause of much trouble by biting the horses on their withers. The injury is generally not so much owing to the loss of blood as to the inflammation which the pressure of the saddle afterwards produces. The whole circumstance has lately been doubted in England; I was therefore fortunate in being present when one was actually caught on a horse’s back. We were bivouacking late one evening near Coquimbo, in Chili, when my servant, noticing that one of the horses was very restive, went to see what was the matter, and, fancying he could detect something, suddenly put his hand on the beast’s withers and secured the Vampire.”
These Bats present, in the extraordinary differentiation of the manducatory and digestive apparatus, a departure from the type of other members of the family unparalleled in any of the other orders of Mammalia, standing apart from all other mammals as being fitted only for a diet of blood, and capable of sustaining life upon that alone. Travellers describe the wounds inflicted by the large sharp-edged incisors as similar to those caused by a razor when shaving: a portion of the skin being shaved off and a large number of severed capillary vessels thus exposed, from which a constant flow of blood is maintained. From this source the blood is drawn through the exceedingly narrow gullet—too narrow for anything solid to pass—into the intestine-like stomach, whence it is probably gradually drawn off during the slow process of digestion, while the animal, sated with food, is hanging in a state of torpidity from the roof of a cave or the inner side of a hollow tree.
Desmodus.[638]—No true molar, and no calcar. The Common Vampire (D. rufus) is widely spread over the tropical and subtropical parts of Central and South America from Oaxaca to Southern Brazil and Chili. It is a comparatively small species, a little larger than the common Noctule, the head and body being about 3 inches in length, the forearm 2½, with a remarkably long and strong thumb; it is destitute of a tail, and has a peculiar physiognomy, well represented in Fig. 322. The body is covered with rather short fur of a reddish-brown colour, but varying in shade; the extremities of the hairs being sometimes ashy. The teeth are peculiar and admirably adapted for the purposes for which they are employed. The upper incisor is greatly enlarged, and of somewhat triangular shape (Fig. 323); the canine, although smaller than the incisor, is large and sharp; but the cheek-teeth are very small, with laterally compressed crowns rising but slightly above the level of the gum, their longitudinally disposed cutting-edges being continuous with the base of the canine and with each other. The lower incisors are small, bifid, and separated from the canine, with a space in front. The lower cheek-teeth are narrow, like those in the upper jaw, but the anterior tooth is slightly larger than the others, and separated by a small space from the canine. Behind the lower incisors the jaw is deeply hollowed out to receive the extremities of the large upper incisors. The exceedingly narrow œsophagus opens at right angles into the slender, intestine-like stomach, which almost immediately terminates on the right, without a distinct pylorus, in the duodenum, but on the left forms a greatly elongated fundus, bent and folded upon itself, appearing at first sight like part of the intestines. This cardiac extremity of the stomach is, for a short distance, to the left of the entrance of the œsophagus, still very narrow, but soon increases in size, till near its termination it attains a diameter quite three times that of the short pyloric portion. The length of this cardiac diverticulum of the stomach appears to vary from 2 to 6 inches, the size in each specimen probably depending on the amount of food obtained by the animal before it was captured.
Diphylla.[639]—A small true molar in each jaw, and a rudimentary calcar. The single species D. ecaudata inhabits Brazil, and appears to be much less abundant than Desmodus rufus, from which, in addition to the characters already mentioned, it is distinguished by its slightly smaller size, the absence of a groove in the front of the lower lip, the non-development of the interfemoral membrane in the centre, and the peculiar form of the lower incisors, which are much expanded in the direction of the jaws and pectinated, forming a semicircular row touching each other, the outer pair being wider than the inner ones, and having six notches, the inner pair having only three notches.
Fossil Phyllostomatidæ.—Remains of Vampyrus spectrum, as well as of several species of Phyllostoma or closely allied types, are found in the cavern deposits of Brazil. The mandible of a large Bat from the Upper Eocene Phosphorites of Central France, described as Necromantis, has been referred to this family—a determination which, if confirmed, will be of great interest from a distributional point of view.
Bibliography of Chiroptera.—G. E. Dobson, Catalogue of the Chiroptera in the Collection of the British Museum, 1878, including descriptions of all the species of Bats then known; subsequent papers by the same author in Rep. Brit. Assoc., Proc. Zool. Soc., Ann. Mag. Nat. Hist., and Bull. Soc. Zool. de France; by Peters in Monatsb. Akad. Wiss. Berlin; by O. Thomas in Ann. Mag. Nat. Hist., Proc. Zool. Soc., and Ann. Mus. Genova; and by J. Scully in Ann. Mag. Nat. Hist. and Journ. As. Soc. Bengal; H. A. Robin, Recherches Anatomiques sur les Mammifères de l’Ordre des Chiroptères, Paris, 1881; W. T. Blanford, “Notes on Indian Chiroptera,” Journ. As. Soc. Bengal, vol. lviii. (1888). See also papers by Jentink, Bocage, and others.