An old chapter of the geological record, with a new interpretation: or, rock-metamorphism ... and its resultant imitations of organisms. With an introduction giving an annotated history of the controversy on the so-called 'Eozoon Canadense' ... By ... W. K. ... and T. H. R

Front matter

FRONTISPIECE Plate IX Tic i— Development of Chrysottle, from the incipient (or) to the completed state (d), showing the origin of the "proper wall" of "Eozoon" (Diagram) . Fig 2.-£ozoon Canadense" from Ottawa, Canada, showing the following changes ; chrysotile(b)into"proper wall "(d), and flocculent serpentine (c) into "canal system" (c*). Fig. 3. -Lamellar graphic granite from Tarbert, Hebrides.* its lamellar and fibrous structures are considered to be organic by Eozoomsts. Pinx W.K H__.nh__T*l. lith AN OLD CHAPTER OP TEE GEOLOGICAL RECORD WITH A NEW INTERPRETATION: OR, ROCK-MET AM ORPHISM (ESPECIALLY THE METHYLOSED KIND) AND ITS RESULTANT IMITATIONS OF ORGANISMS. WITH AN

Introduction

GIVING AN ANNOTATED HISTORY OP THE CONTROVERSY ON THE SO-CALLED " EOZOON canadense;' AND AN

Appendix

. BY Professors W. KING, Sc.D. etc., •£? T. H. ItOWNEY, Ph.D. etc., OF THE QUEEN'S COLLEGE, GALWAY, AND THE QUEEN's UNIVERSITY IN IEELAND. LONDON: JOHN VAN VOORST, 1 PATERNOSTER RO^. MDCCCLXXXI. AtEEE FLAMMAM. PRINTED BY TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET. CONTENTS. Pages Preface v-viii Introduction ix-lvii Chapter I. The different Kinds of Rocks treated of 1-3 II. The Mineral Characters of Ophites and related Rocks . . 4-7 III. Structural Characters of Ophites and related Rocks .... 8-11 IV. Origin of certain of their Mineral, Structural, and Chemical Characters 12-27 V. Mineralized and Methylosed Metamorphic Rocks 28-33 VI. Why some Metamorphic Rocks have been Mineralized and others Methylosed 34, 35 VII. Methylotic Origin of Ophites 36-42 VIII. Serpentinization effected in certain Deposits without the intervention of Mineralization 43, 44 IX.

Many Ophites were Sediments, and others Igneous Rocks originally 45, 46 X. Methylotic Origin of Hemithrenes and other related Calcitic Rocks 47-59 XI. On the Origin of the Minerals characteristic of Ophites and related Rocks —of Peridote in particular 60-71 XII. On the Origin of the Archæan " Crystalline Limestones " of Canada 72-82 a CONTENTS. Chapter Pag66 XIII. Why are Limestones comparatively rare in the Formations immediately succeeding the Archæans? .... 8-3-88 XIV. Some Crystalline Limestones have been simply Mineralized 89,90 XV. Dolomites and Dolomitic Rocks have undergone Methylosis 91—95 XVI. The Chrono-Geological Range of Ophites and related Rocks, and the Age of their Methylosis 96, 97

APPENDIX.

. Th-alassa and Xera in the Permian Period 99-106 Supplementary Note A. — Rock-jointing in relation to Phenomena in Physical Geography and Physical Geology. . . . 107-117 Supplementary Note B. — On the Crystalline Bodies of the Sunderland Permian Magnesian Limestone 118, 119 Supplementary Note C. — Certain Limestones are of Mechanical Origin 120, 121 Description of the Plates 123-126 Index 127-142 PEEFACE. Since the publication of Bischof 's ' Lehrbuch der chemischen und physikalischen Geologie' (1847-54), seldom has any thing excited more sustained interest among geologists than the question as to the nature and origin of metamorphic rocks. At the Paris Exhibition, in 1878, an International Congress, comprising many eminent geologists, was convoked, one of the main objects of which was to consider the problem of metamorphism.

Re searches having the same purpose in view have been promoted by grants from the Government Scientific Research Fund at the recommendation of the Royal Society, and from the British Association. Some sixteen years past the alleged discovery of the so-called "Eozoon Canadense " gave a marked impetus to the study of metamorphic geology ; and of late years microscopic observations on metamorphosed rocks and their component minerals have been sedulously pursued. The result of all this is that a vast body of evidence has been gathered together, throwing much new light on the subject in question. Nevertheless, if the latest exposition of rock-metamorphism is to be taken as correctly representing its present state, the subject, it would rather appear, has all along been stagnant, having made no progress since Lyell began to write on it — more than forty years ago !

Dr. Ramsay, in his Address lately delivered at Swansea as President of the British Association, declares, without any reservation, that in metamorphic rocks " there is little or no development of new material ;" and he VI

Preface

. accordantly maintains that they have been simply mineralized ■" sandstones have been converted into quartzites," and so on, — using almost the same terms as Lyell did, and after the lapse of nearly half a century. This latter-day exposition of metamorphism, the writers feel, .affords indubitable proof that the present work is imperatively called for to meet the requirements of a large body of geological students. Having laboured at the subject for fifteen years (aided to some extent by a grant from the Government Fund), they have determined the existence of two strongly differentiated groups of metamorphic rocks — mineralized and methylosed. They are also enabled to show that the characters of the latter group have been developed by the decomposing action of carbonated solutions on siliceous minerals ; that essentially silacid rocks, which have been permeated by solvents of the kind, have be come variously transmuted and transformed — in the one case having had their mineral silicates for the most part replaced by mineral carbonates (calcite &c), — in the other the same siliceous minerals, where simply affected by partial erosion and replacement, having become shaped into a variety of residual configurations that have been mistaken for organic structures, as in " Eozoon Canadense."

Moreover the above phenomena enable the writers to show that both bedded and dyke shaped masses on a large scale exhibit corresponding chemical changes ; so that what were once essentially siliceous rocks are now ophites, hemithrenes, and the like, — in which it cannot be said that " there is little or no development of new material " and which, in short, clearly prove that there are numerous other metamorphic rocks besides those that are simply mineralized. Just before the " creature of the dawn " made its advent, mineral pseudomorphism was labouring under great bewilder-

PREFACE.

. VII ment. The opinion on the subject, which had been founded on the researches of Blum, Bischof, Rose, and others, was encounter ing more or less hostility from Scheerer, Naumann, Delesse, and Sterry Hunt. The pseudomorphic origin of serpentine, which had been strongly contended for by the first group of scientists, was uncompromisingly opposed by certain of the latter, especially Sterry Hunt, who, with the fact before him that this mineral occurs, forming vast rock-masses, amongst the old strati fied crystalline deposits (Archæans) of Canada, unhesitatingly declared it to be neither pseudomorphic, nor metamorphic, but a crystallized precipitate, chemically thrown down by the primæval ocean. At last "Eozoon Canadense " appeared on the scene. Chiming in to some extent with Sterry Hunt's " novel doctrine," it was at once enthusiastically accepted by the highest authorities in geology as resolving the vexed question attaching to serpentine and some other Archæan problems ; at the same time it was held up before the eyes of a wondering and con fiding world as the first-born of life on our planet — protoplasm in vast flakes invested with a calcareous covering, and rivalling coral reefs in magnitude ! It will be our object in the following pages to show that both doctrines are absolutely fallacious. 1858. 1859. 1863,

INTRODUCTION.

. The first announcement in connexion with the subject of "Eozoon" was made by the late Sir Wm. E. Logan, Director- General of the Geological Survey of Canada, in his Report of the year 1858. Sir Wm. E. Logan exhibited at the Meeting of the American Association for the Advancement of Science at Springfield, in August 1859, some Stromatopora-like specimens (noticed in the above Report) from the Grand Calumet and Perth (Canada), which he was " disposed to look upon as fossils"*. Report of the Geology of Canada, 1863. Sir W. E. Logan. In this Report (pp. 48, 49) the discovery of specimens, supposed to be fossils, is noticed as having been made "by Mr. J. M'Mullen, of the Canada Geological Commission, in the crystalline limestone of the Grand Calumet (river Ottawa), which present parallel or apparently concentric layers, com posed of crystalline pyroxene, while the interstices are filled with crystalline carbonate of lime.

Dr. James Wilson, of Perth, found loose masses of limestone near the same place containing similar forms — the layers composed of dark green concretionary serpentine, while the interstices are filled with crystalline dolomite. If both are regarded as the results of unaided mineral arrangement, it would seem strange that identical forms should be derived from minerals of such different * Quarterly Journal of the Geological Society, vol. xxi. p. 48. introduction. X 1804, 1864, 1864. 1804. composition. If the specimens had been obtained from the altered rocks of the Lower Silurian series, there would have been little hesitation in pronouncing them to be fossils." American Journal of Science, March 1864, p. 273. Sir W. E.Logan announced that Dr. Dawson had discovered in the Canadian ophite structures which it was decidedly his belief were organic and foraminiferal.

On the Occurrence of Organic Remains in the Laurentian Rocks of Canada. By Sir W. E. Logan, F.R.S., F.G.S. ; with Communications by J. W. Dawson, LL.D, F.R.S., on the Structure, and by T. Sterry Hunt, F.R.S., on the Mineralogy of the same remains. Paper read at the Bath Meeting of the British Association, September 1864. On the Structure of certain Organic Remains in the Laurentian Limestones of Canada. Dr. J. W. Dawson. Q. J. G. S. vol. xxi. pp. 51-59. Additional Note on the Structure and Affinities of Eozoon Canadense. Dr. W. B. Carpenter. Op. cit. pp. 59-66. Both writers assume that the calcareous or dolomitic layers of the specimens brought under notice by Logan constitute the skeletal portion of "Eozoon Canadense," and that the siliceous layers, whether serpentine, white pyroxene, or loganite, are casts of its cells or chambers.

Dawson, having detected branching configura tions and rods or plates in the " skeleton," and taking them for casts of canals and stolons, identified them with the canal system and stolons of a foraminiferal organism ; and Carpenter, observing a fibrous lamina often surrounding the " chambers," pronounced its fibres to be casts of tubuli such as characterize the proper wall of a nummuline foraminifer. The serpentine layers frequently present themselves more or less excavated and divided ; but often they are broken up into short plates and detached spheroids irregularly lobulatcd. The presumed organism in the former case is

INTRODUCTION.

. XI 1864, 1864. 1864, 1864. 1865. 1805. 1865. said to be the " lamellated," and the latter the " acervuline " variety. On the Occurrence of Organic Remains in the Laurentian Rocks of Canada. Sir W.E. Logan. Q.J.G.S. vol. xxi. pp. 45-50. On the Mineralogy of certain Organic Remains from the Laurentian Rocks of Canada. Dr. T. Sterry Hunt. Op. cit. pp. 67-71. On the Structure and Affinities of Eozoon Canadense. Letter to the President of the Royal Society. Dr. W. B. Carpenter. Proc. Roy. Soc. vol. xiii. pp. 545-549. Geological Magazine. Vol. ii. pp. 87, 88, Dec. 27, 1864. Announcement by Mr. W. A. Sandford, F. G.S. , of his discovery of "Eozoon Canadense" in Connemara marble from the Bina bola Mountains ; which "T. R. J.," at the same time, announced he had " verified by experiment." " The various formed chambers, the shell of varying thickness, either very thin and traversed with fine tubuli, the silicate filling which (when bared) resembles white velvet-pile, or thick and traversed with brush-like threads, representing the pseudopodian passages of the ' supplemental shell' (or 'vascular system'), are all present."

"Appendix" to a reprint of Dr. Dawson's Memoir (a.d. 1864) in Canadian Naturalist, April 1865. Dr. Dawson, who had previously observed " traces of organic structure in the Connemara marble, but not in so far as can be made out of the character of Eozoon," declares that "it is gratifying to find in recent British publications notices to the effect that Mr. Sandford has found the structure of Eozoon in the Laurentian limestones of Ireland." On the Structure, Affinities, and Geological Position of Eozoon Canadense. Dr. W. B. Carpenter. Intellectual Observer, vol. vii. On the oldest known Fossil, Eozoon Canadense, of the Laurentian Rocks of Canada; its place, structure, and significance. Prof. T. Rupert Jones. Popular Science Review, vol.

INTRODUCTION.

. 1865, The following letter appeared in the 'Reader,' June 10, 1865, p. 660 :— " The Eozoon Canadense. " Queen's College, Galway, June 3, 1865. "We beg permission to publish the following statement through the medium of your widely-circulated Journal : — "For several weeks past we have been engaged in investigating the microscopic structure of the serpentine of Connemara in comparison with that of a similar rock occurring in Canada, which has attracted so much attention of late. For a considerable portion of the time we entertained the opinion, in common with Sir William Logan, Drs. Dawson, Sterry Hunt, Carpenter, and Professor Rupert Jones, that the Canadian serpentine is of organic origin, the result of the growth of an extinct foraminifer called Eozoon Canadense ; it was also our belief for a while that the Connemara rock had originated from a similar organism.

Gradually of late, however, we have been reluctantly compelled to change our opinions. " It is now our conviction that all the parts, in serpentine, which have been taken for the skeleton-structures of a foraminifer are nothing more than the effect of crystallization and segregation. "It would have given us unalloyed pleasure, had we been able to state that our investigations had confirmed those of the eminent authorities to whom reference has been made, as it was purely in this spirit that we commenced our labours ; and also, we may observe, with the desire to ascertain if the serpentine of Connemara and the other rocks with which it is interstratified, belonged to the Laurentian period. " We purpose at an early opportunity to lay before the public all the evidences and considerations which bear us out in our present opinion. " We are, Sir, yours very truly &c., " William King, Professor of Mineralogy and Geology. "Thomas H. Rowney, Ph.D., Professor of Chemistry."

INTRODUCTION.

. XIII 1865, 1865. 1865. 1865. 1866. "The Eozoon Canadense." A letter, signed " William B. Carpenter," appeared in a following number of the ' Reader.' The writer asserts that the " conformity " between " Conne mara serpentine " and " that of the least characteristic part of the Canadian fossil " is " so close as to leave no doubt in my mind as to the organic origin of the former." Next, he makes a characteristic personal attack on the writers of the preceding letter, " advisedly " remarking on the " audacity " of the one in presuming to dispute the organic origin of Eozoon, and impliedly charging the other with incompetency. A short reply, signed " William King," appeared in the next number of the ' Reader'*. The Cambrian Rocks of the British Islands. W. Hellier Baily. Geological Magazine, vol. ii. p. 388.

Mr. Bailey expresses his doubt that " Eozoon," " the thing in question, was a fossil at all" (Journ. Geol. Soc. Dublin, vol. i. N. S.). " Eozoon " having been brought under the notice of the Geo logical Section of the British Association, held in Birmingham of this year, Professor R. Harkness declared his disbelief iu it ('Reader/ Sept. 30, 1865). On the so-called " Eozoonal Rock." Professors W. King and T. H. Rowney. Q. J. G. S. vol. xxii. pp. 185-218. In this memoir evidences are adduced to show that the " calcareous skeleton " and the " chamber casts " of " Eozoon Cana dense " stand in the same relation to each other as the calcitic matrix and its included mineral silicates in a number of rocks, — that the lamellated and the acervuline varieties are strictly paral leled, the one by a rock in Scandinavia consisting of alternating layers of calcite and a hornblendic mineral, the other by cocco litic marbles of Tyrol, Delaware, and elsewhere, — that the * Another letter, dated July 24, 1865, on a subject arising out of our announcement, and introduced by Dr. Carpenter, was published in a succeeding number.

INTRODUCTION.

. " canal system " is paralleled by ramose foliations of metaxite, and is analogous to the coralloids of the magnesian limestone common at Sunderland, — that the " proper wall " is a modification of chrysotile, — in short, that all the features diagnosed for Eozoon are of purely inorganic origin, resulting from chemical and structural changes in the minerals severally composing them. Previously to the publication of our paper no reference had been made by Logan, Dawson, Carpenter, Sterry Hunt, or Rupert Jones, in their respective writings on " Eozoon," to the presence of chrysotile in frequent association with this presumed fossil. In fact, serpentine in all its forms and relations was altogether ignored. At the time referred to, the subject of mineral pseudomorphism was in an extremely unsettled state.

The opinion respecting it, as advocated by Blum and others, was being opposed by Scheerer, Naumann, and Delesse, and especially by Sterry Hunt, who was enthusiastically propagating his " novel doctrine " — the chemical precipitation of metamorphic rocks ; so that the obvious facts connected with eozoonal features escaped being sufficiently examined from a mineral point of view. Moreover the origin of serpentine, one of the metamorphics in question, was equally a bone of contention — its protean character, both structural and chemical, its occurring indifferently as intrusive dykes and sedi mentary beds, its playing a prominent part in what was taken to be the earliest sea-born organism of our planet, and the little then known with respect to chemical changes in rocks, all taken together, caused mineral pseudomorphism to be thrown into the background — to be repudiated as having any thing to do with the " creature of the dawn."

In addition to other points introduced by Dr. S. Hunt in his memoir of 1864, and which are duly noticed in the following pages, he describes the mineralogy of "Eozoon " from one ofthe specimens which first led Logan to suspect their organic origin. A specimen of the kind has been lately sent (April 1881) to us by Mr. R. Damon, F.G.S., who received it from Dr.

INTRODUCTION.

. XV Dawson : it is labelled " Eozoon — special variety — mineralized with loganite;" but no locality is mentioned. Hunt's specimens were from Burgess, Canada. Their layers are of two kinds : one, " a somewhat ferriferous dolomite," yielded on analysis "carbonate of magnesia 40*7, carbonate of lime, with a little per oxide of iron, 59*0 = 99' 7;" and the other, a dark green mineral silicate, called loganite, yielded " silica 35*14, alumina 10-15, magnesia 3L47, protoxide of iron 8"60, water 14-64=100-00." It is consequently a hydrous alumino-magnesian silicate related to chlorite, and a true serpentinous mineral (pp. 4, 5). The original loganite occurs in prismatic crystals, which, from their measurements, Dana does not hesitate to declare to be pseudo morphs after hornblende. Serpentine is another mineral equally pseudomorphic after hornblende.

Therefore the fact that both serpentine and loganite (which are alike pseudomorphic after the same mineral) form "chamber-casts of Eozoon" affords no support to the presumed organic origin of these features. Besides serpentine and loganite, the mineral silicate referred to by Logan and Hunt under the name of " white pyroxene " also " occurs in immediate contact with a layer " of the former*. " White pyroxene," we have reason to consider, is another pseudomorph after either hornblende or augite ; so that, to some extent, it also invalidates the organic hypothesis. The specimen we have received from Mr. Damon does not quite agree with Sterry Hunt's. It is made up of two kinds of layers, not well defined, however, as such. The loganite, which forms one ofthe kinds, is in dark-green crystalloids, variously clustered together, and very seldom showing any traces of proper cleavage ; as their " fracture is granular."

The other layers have an opaque white colour ; but, instead of consisting of calcite or dolomite (miemitet), they are composed of what appears to be " white pyroxene :" imbedded in these layers are siliceous crystalloids of a pale-green colour, in which respect * Quart. Journ. Geol. Soc. vol. xxi. p. 67. t We find it advantageous to restrict the term dolomite to rocks, and apply that of miemite (one of the names in use) to their mineral representative.

INTRODUCTION.

. they appear to consist of serpentine. The crystalloids of " white pyroxene " are strongly affected with cleavage, which is more or less represented by open gashes — the openness of which is disclosed by an infilling of calcite : it frequently happens that the cleavage is imperfectly developed, especially when the mineral is in a translucent condition ; which is occasionally the case. The crystalloids when much gashed are reduced to plates more or less separated ; and in many instances the plates are converted into fibres, somewhat mimetic of those characteristic of the " proper wall " (see woodcut, p. lvii) . No cases have occurred to us of typical " canal system." In numerous cases the reduction of the crystalloids has resulted in the complete removal of their substance, and its replacement by calcite.

Although our specimen of "Eozoon mineralized with loganite" differs from those which S. Hunt had under his observa tion, we can quite conceive the existence of specimens of the latter kind, inasmuch as the crystalloids through solvent action may have disappeared altogether, and been replaced by " ferriferous dolomite." The specimen closely corresponds with a rock occurring in Connemara, made up of layers of serpentine and malacolite, and which we have elsewhere (p. 2) called malacolophyte : the resemblance is so close that the crystalloids of malacolite in the latter are widely gashed with corroded cleavage, and the gashes similarly filled with calcite. This peculiarity is so much de veloped that when it first came under our notice we were immediately struck with the idea that the calcite had originated from chemical changes in the malacolite.

It is now fifteen years since we formed this opinion ; and it has been completely estabbshed by our observations on malacolite or a closely allied mineral from Ceylon, Aker (Finland), Isle of Skye, New Jersey, Porthlisky (Pembrokeshire), and Mont St. Philippe (Vosges). We take the specimen of " Eozoon mineralized with loganite " as another evidence in our favour. We now beg to call Dr. Hunt's attention to one other point in

INTRODUCTION.

. XVII the mineralogy of "Eozoon Canadense." He has brought under notice a specimen of the presumed fossil from the Calumet, which " exhibits the whole of the sarcode replaced by serpentine ; while, in another one from the same locabty, a layer of pale green translucent serpentine occurs in immediate contact with white pyroxene." There is very little difference, then, between the latter speci men and the one we have had under notice. Yes, we beg pardon, there is a difference : in Sterry Hunt's specimen there are " very thin " calcareous layers (" septa ") which run " transverse to the plane of contact of the two minerals"; yet they are seen to traverse both the pyroxene and the serpentine without any interruption or change." It is to be apprehended that Dr. Hunt, in bringing forward this specimen with its calca reous septa intersecting the serpentine layers, lays himself open to the doubt of his being sufficiently acquainted with the struc ture of "Eozoon Canadense " as diagnosed by his colleagues.

No view which contends for the inorganic origin of the different eozoonal features can be considered satisfactory unless it be consistent with facts pertaining to mineralogy, geology, or chemistry. With respect to the " chamber-casts " and the " proper wall," their origin, as products answering to these terms, will be made clear in the following pages ; but as regards the " canal system," a point in connexion therewith requires some consideration ; for we freely admit that this part possesses peculiarities which seemingly do not strictly accord with ordinary mineral developments, except, it may be, in the case of certain dendritic bodies characteristic of " moss agates." But although at the commencement of our examination of "Eozoon " we felt inclined to identify the " canal system" with the latter products, it was never quite clear to us that we were in the line of the correct view, especially when there were palpable evidences at hand showing that the variety which generally presents itself in the Canadian " eozoonal " ophite had originated through a wasting or decretory process of its component subb

INTRODUCTION.

. stance (flocculite), whereas the dendritic bodies referred to are unmistakably the indirect products of crystalline development. The point now introduced consists of the flocculent variety of the "canal system," which, composed of a homogeneous or structureless substance, is unlike in its arborescent forms ordinary crystalline products ; while its branchless resemble casts of tubes and other cavities conceivably produced by tunnel-enclosed vessels of an organism, as predicated of them by eozoonists. We must except in this connexion a variety of the " canal system" consisting of malacolite, as it is palpable beyond dispute that its branchless have resulted from the decretion of clusters of irregularly arranged crystalloids of a mineral readily affected by solvent action along its eminent cleavage-divisions, and thus etched into shapes equally simulative of arborescent growths.

But in the case ofthe flocculent variety of the "canal system" we are dealing with bodies possessing forms which, although we maintain that they have been equally produced by decretion, cannot be positively said to have been predetermined by cleavage structure *. We do not propose to enter on an explanation of this point ; all we have to do is to prove the existence of examples simulative of organic features, in the elaboration of which crystal line forces alone have been concerned, and which are apparently as unlike crystalline products as the typical examples of flocculent " canal system." We refer to the foliaceous expansions charac teristic of the mineral silicate metaxite, also the coralloids and other configurations of the Sunderland magnesian limestone. First, the configurations in metaxite have a strikingly organic aspect ; and it is undeniable that they are purely of mineral origin.

It must also be remarked that this mineral, like floccu lite, is without internal structure ; properly speaking, it has a pasty consistency. Moreover it is closely related to, if not an * Still we have already adduced the most conclusive evidence that rod-like cylindrical processes in serpentine (undergoing change into flocculite) have had their shape determined by rectangular prismatic cleavage.— See Proc. Roy. Irish Acad. vol. x. pi. xliii. fig. 8.

INTRODUCTION.

. XIX 1866, allomorph of, serpentine ; and, what is equally significant, the expansions are included in a calcareous matrix. It may there fore be confidently assumed that the point which at first sight appears to favour organic intervention in the production of the flocculent "canal system," altogether ceases to be such in presence of the foliaceous configurations of metaxite. Respecting the magnesian Umestone coralloids, and other forms, we have on different occasions spoken of them as gigantic similitudes of the " canal system," " stolons," and " chambers " of "Eozoon." We cannot say of them, any more than it can be said of the metaxitic configurations, that they have been elaborated precisely in the same way as the " eozonal " structures. It is sufficient for our purpose that they strikingly resemble not only corals and other organisms, but casts of tubes, chambers, and other structures of the kind just referred to, in their external form, and have seemingly no relation in this respect to ordi nary crystalline or mineral developments; yet every one who has studied them in situ is compelled to admit that they are solely the products of inorganic agencies.

As such, then, it may be safely asserted that in relegating the " canal system " of "Eozoon Canadense" to the inorganic kingdom, we are supported not only by evidences of the most decisive character, but by facts strictly belonging to mineralogy and the related sciences. As further justifying this step, it may be mentioned that the coralloids, &c, and their matrix, are demonstratively secondary products that have resulted from chemical changes (Chap. XV. and pp. 118, 119). Supplemental Notes on the Structure and Affinities of Eozoon Canadense. Dr. W. B. Carpenter. Q. J. G. S. vol. xxii. pp. 219-228. To which is added a note containing an extract from a com munication, dated March 28th, from Dr. Dawson announcing his discovery of " the occurrence of Eozoon preserved simply in carbonate of lime." XX

INTRODUCTION.

. 1866. 1866. 1866, 1866, In these " Notes " Dr. Carpenter declares that he is " prepared to maintain the organic origin of Eozoon on the broad basis of cumulative evidence afforded by the combination, in every single mass, of an assemblage of features which can only be separately paralleled elsewhere, and in the repetition of the combination with the most wonderful exactness over " areas of immense extent" (will be further noticed, a.d. 1869). Ueber das Vorkommen von Eozoon in dem ostbayerisches Urgebirge. Dr. C. Giimbel. Sitz. des kon. bayer. Akad. d. Wiss. zu Miinchen, 1866. The author makes known the occurrence in beds of serpentine marble in Bavaria of eozoonal structures, certain of which he considers to represent a new species — " Eozoon Bavaricum." We noticed in our memoir, last considered, as proving the mineral origin of " Eozoon," the presence in various calcitic marbles (hemithrenes) in Scandinavia, Isle of Tyree, New Jersey, of rounded crystalloids of pargasite, chondrodite, hornblende, &c. Dr. Giimbel declares " there can scarcely remain a doubt that the curiously rounded grains imbedded in the crystalline limestones of Pargas represent the casts of sarcode chambers, as in Eozoon ; and that they are consequently of organic origin."