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Whenever possible, these have been omitted from filming/ II se peut que certaines pages blanches ajoutdes lors d'une restauration apparaissent dans le texte, mais, lorsque cela 6tait possible, ces pages n'ont pas 6t6 filmdes. Additional comments:/ Commentaires suppl6mentaires: L'Institut a microfilm^ le meilleur exemplaire qu'il lui a 6t6 possible de se procurer. Les details de cet exemplaire qui sont peut-dtre uniques du point de vue bibliographique, qui peuvent modifier une image reproduite, ou qui peuvent exiger une modification dans la methods normale de filmage sont indiquis ci-dessous. I — I Coloured pages/ Pages de couleur Pages dan-:n a tiiick band of gneiss. In front of Lowe'.s excavation, and a]>i>arently overlying tho lirae- Btone exposed in it, is a narrow ledge of fine-grained gneiss ; and beyond this other and probably overlying lime.stone appears, liokling pyroxene and mica. The whole vertical thickness of the limestone exposed can scarcely exceed !')() feet; but this is probably only a small part of the development of the l)and at this place. In the strike of tho limestone to the south it appears to bend abruptly, or to bo thrown by a fault, to tlie south-east, the gneiss and diorite coming forward into a line with it, and the limestone appearing in a little l)are knoll in front of these. On the surface of this limestone were found some fine specimens of weathered Kozooik I examined carefully the relation of the bedded serpentine and the veins of chrysotile or fibrous serpentine to the limestone. The compact serj)entine is evidently an original part of the deposit, occurring in layers and lenticular concretions. In some b(>ds it shows no indication of the structure of Eozoon ; but in others it fills tho cavities of the fossils, and there are many regular layers of fragmental /'mzdhh of considerable thickness in which it fills the cells, while in other layers interstratified with these the fossil is associated with dohmiite. I satisfied myself on this jmint not only on the ground, but also by taking away large specimens represent- ing several thin layers, and treating them with dilute acid so as to being out the structinv. Tho following is a siTtion of such a speci- men, T),! in(t!ies in verticjtl thickness, treatecl with acid and examined with ;i lens: — i f 68 J. W. DAWSON ON lUl-; (XX'tKUKXCK 01' 1. Limostoiu" Willi orystulu ol' dulomiti' initl ii tVw friiginents of AVoo». 2. Fiiio-j^rainiHl liuu'stniu' witli ^fraiiult's ol' st'riu'iitiiio -tin* latter lilliug the cliainlH'rli't!* of IVngiiicntH ol' F.o:n(»i and sm;»ll globigorino Foramiiiil'era. 3. liiiui'stouo \vitl\ (loloinito and including a tli'n laviT ol' Hcrpcntino as above. 4. Linu'stont' and dolonutf with graiiK* of ^«<'rlH'ntino and i'mginents of Hiipplc- niontal rtki'U'ton of Kacooii. 5. Crystallized doloniile, holding a i'vv/ Iriiginentfl of Juicooii in tho state of c'ulcit 0. «). Limestone witli dissiMninatod serpent i no as alxve, ehaniborlets of F.o:n(m nnd fragments of its snppieineutid skoleton. also small groups of eliamberlets. IM'rhajw globigerine Foranunifem. In other Hpccimeiis a like thickness of rock presented a mass of fra}3;meiit8 of siipplementiil skeleton with the canals injected with serijcntine, and }i,Tanule3 of the same lillinp; tlie chambers. The chrvsolile veins, which are sometimes an inch or more in thickness, Dnt branch off into the most minute fibres, are evidently ultogether Hiibsetiuent in origin to the bedded liinestcme and ser- pentine. They are undoubtedly of a(inc(ms origin, and in their mode of occurrence strongly resemble the veins of fibrous gypsum penetrating the Lower Carboniferous marls of Nova Scotia. They cross the bedding in all directions, and pass through the stnicture of Kozixm, though sometimes running parallel to its lamina) for short distances. They must have been introdticcd after the Eozoon was mineralized, and have evidently no connexion with its structure. In the diagram (1*1. X. fig. 2) L have attcmplcd to represent this relation ; and I have no hesitation in stating that the asserticm that these ehrysotile veins ai'e identical with or similar to the proper wall of I'Jozoon either in structure or distribution, is wholly without foun- dation, other than that which may arise from confounding dissimilar structures accidentally associated witli each other. Some slickcnsided joints lined with a lamellar and fibrous ser- pentine traverse the beds, and, as the ciiiysotile veins sometimes terminate in them, may be older than the latter. These also were observed to cross the masses of luKoao. Few disseminated minerals, other than tliose already mentioned were observed in the Eozoon limestone. A tew detached crystals of mica, pyroxene, and ])yrite were found in the fragmental layers, and also a few rounded particles of quartz, i>ro1)ablv grains of sand. The perfect examples of hozoon, at least those rendered evident by mineralization with serjH-ntine, are confined to certain bands of limestone, and notably to one band— that originally opened by Mr Lowe. In this bed the fossil occurs in patches of various sizes, some of them two feet or more in diameter, and ))ent or folded bv the contortions of the strata; others are much smaller, down to a few inches On the weathered surfaces the specimens mineralized with serpentine project and exhibit their lamination in great perfection resembling very closely the silicificd .Stromato^^on. oi'iho Sv TOUS Ihe lower lamina, arc generally the best developed and with None ness. tlie thickest supi.lomental or internicdi: (in>'jns than in the ordinary acervnline I'JozooH, and the chaniherlets theniselves more eyhndrieid and tDrtu- 0U9. TiieHc Hpeiimens may either be |)orti()iis of the acervuliiie supcrticial part of /ujzonn broken off and separately preserved, or they may const itut(> a distinet varietal form. As the latter sceais on the whole most probable, I would name tliis form variety acervitVinn. These varieties are of mueh more rare oeeurrence tlian tiic ordi- nary typo of Eozoon. The ordinary speeimensof hJozoon found at St. Pierre are mineral- ized with serpentine ; but fragments imbedded in the dolor.iitic limestones have their canals tilled with a transi)arent mineral which. from its optical character, is evidently dolomite, though the (juan- tity obtained was not snfficient for any definite chemical tost. Parts of the canals in these spc^cimens were tilled with calcite, as shown by its dissolving entirely away in a dilute acid. In one of the serpentinous specimens also I have observed that, while portions of the groups of canals, esi)ecially the basal portions, are filled with serpentine, the extremities of the canals and their finer branches present, under polarized light, the aspect of calcite ; and that they are filled with tliis mineral is proved by these ])orlions of the canal- filling being entirely removed when treated with dilute acid. It would thus appear that in tliese specimens, while the terminal ])arts of the canals have been filled with calcite, tlie basal i)ortions have been occupied l)y serpentine. This is noi, however, a new fact, as similar appearances have been already described both by Dr. Car- penter and the writer. In one specimen 1 observed a portion of the fossil entirely replaced by serpentine, the walls of tlu; skel(>ton being represented bv ii lighter-coloured serpentine than that tilling the cham])crs, and still retaining traces of the canals. The walls thus replaced by serpen- tine could be clearly traced into conuexiDU with the portions of those still existing as calcite. This shows that the serpentine, like the quartz in siliciHed shells and corals, has had the jjowor of re- placing the calcite of the fossils; and I believe that its partial action in this way accounts for some irregularities observed in the less pcrftctly preserved specimens. j\or is it impi-obable, as ])r Hunt has already suggested, that some of the masses of serijcntinc and pyroxene on which specimens of /vcoo» are based, may roi)reseiit older and more perfectlv mim^ralized masses of the fossil In some of the specimens of /vcoo., the suporfic-iid lamime are apparently broken and displaced in such a mnnner as to suL-cst the idea that partial disintegration by tlu« wav.vs I.m.I taken place before they were finally buried. It is also ohservnblc that in son.c ot the masses the compression to which tlu«y have been subiected has i.-oduccd a muroscopie faulting, which slightlv displaces the lillll 11 lit « ^ One of the most interesting feal arcs of the Sl.-Pinre limestone. r V I KO/OON CANAUKNSi; AT COIK SI. VIKIJUK. 71 not noticed by previous observers, is the oceurrcnce of layers filled with little globose (rusts of ehainberlets, single or iittuchiul in j^roiijjs, and often exactly resembling the casts of (/lohi(/erin'^ in greensund (IM. X. figs. 4-10). On weathored surfaces they were often espetiially striking when examined with the lens. In some cases the chamberlets Bcetn to have been merely lined with serpentine, so that they weather into hollow shells. The wmUs of these chamberlets have liad the same tubulated structure as hhzoon (tig. 4) ; so that they are in their essen- tial characters minute acervuline specimens of that species, and similar to those which 1 described in my paper of 1HG7* as occurring in the limestones of Long Lake and Wentwortli, and also in the loganitc filling the ch;im))ers of sj)ecimens of Kozooa fn)m Jhirgess. Some of them are connected with each other by necks or pnxiesses, in the manner of the groups of chambfn'lets d(>scribed by(iiimbelas occur- ring in a limestone from Finland, examined by him. That they are organic I cannot doubt, and also that they have been distributed by currents over tlie surface of the layers ahmg with fragments of Eozoon. Whether they are connected with that fossil or are speci- fically distinct may admit, of more doubt. They may be merely minute portions detached from the acervuline surface of hhzoon, and possildy of the Jiature of reproductive buds. On the other hand, they may be distinct organisms growing in the manner of Olohli/crlna. As this is at present uncertain, and as it is convenient to have some name for tliem, 1 propose to term them Arc/upo.yikip- ritxr, understanding by that name minute Fora mini feral organisms, having the form an I mode of aggregation of Glofji;/ertita, but with the proper wall of I'hzoon. In slicing one of my specimens from Cote St. Pierre I have recently observed a very interesting peculiarity of structure, which deserves mention. It is an abnormal thickening of the calcareous wall in patches extending across the thickness of four or five lamelhc, the laiter becoming sliglitly bent in approaching the thickened portion. This thickened portion is traversed by regu- larly placed parallel canals of large size, filled with dolomite, while the intervening calcite presents a very fine dendritic tubulation. The longitudinal axes of the canals he nearly in the plane of the adjacent lamina?. This structure reminds an observer of the CiXiiostroma type of Stromcftopom, and may be either an abnormal growth of hjozoon, cons(Mpioiit on some injury, or a parasitic mass of some Stromatoporoid organism finally overgrown by the Eozoon. The structure of the dolomite shows that it first incrusted the interior of the canals, and subse(piently filled them — an appearance which T have also observed in some of the larger canals filled with serpentine, and which is very instructive as to their true nature. From the above facts the true nature of Eozoon may, I think, be rendered evident to any geologist, however little he may have made the fossil Foraminifera a subject of study. The theories as to its -,x>rigin may be summed up thus : — 1 . The complicated theory of pseudomorphism and replacement, ■-ir * Quiiit. Joiirn. Gc >1. Sop. vol. xxiii. p. 200. 78" J. W. DAW80N ON TUE OWURKKNC'I; OV iitlvocatcd by Messrs. Kowiioy aiul Kiiijj;, may hv diHinisHod at oiico. Iiidepcndontly of tlic iiisuiu'iubli' chomicul ditficulticH which have been pointed out by Dr. Hunt*, iind which ho j)r()]ioHe8 to discuHH more fully in his jMipers on Clii'iniciil (Jeulogy, now in the press, we hiive the further facts timt no repliicement of serpentiiu- by eulcitc is indicated by the relntions of these niin(;ruls to eueh other, while .siu'h repluceniont as does occur is in the other direction, or the chanj^o of ealcite into scrpentitu', us evidenced by the state of preservation of Konie specimens of /•Jicooii, above referred lo. Further, tliih theory fails to give any explanation of the speciniens mineralized by pyroxene, dolomite, and ealcite, or to account for the nunimulinc wall, exeosed posisilde that Kozoon is merely a moditieation ot these concretionary forms. In this case, the filling of each lamina and chamberlet of Eozaon must be regarded as a sei)arate concretion ; and even if we could sup'^/ose some H[)ecial cause to give regularity and uniformity to such concretions in some places and not in others, wo still have unaccounted for the canals and tubuli, ()»■ the delicate threads of serjjentine representing them. Further, we nave to sup- pose that a tendency to this regular and coraidicated arrangement has affected in the same way minerals so diverse as serpentine, loganite, pyroxene, and dolomite. 3. The only remaining theory is that of infiltration by serpentine of cavities previously existing in the ealcite. There is no chemical objection to this, inasmuch as we know of the infiltration of fossils in other formations by minerals akin to Reri)entine; and in these limestones the veins of fibrous 8(!rpentine have evidently been intro- duced by aqueous action subsequently to the production or fossiliza- tion of the Eozoon. Further, the white pyroxene of the Laurentian limestones, and the loganite and dolomite, arc all known to have been produced by aqueous deposition. The only ([uestion remaining is. Whence came the original ealcite skeleton with laminic, chambers, canals, and tubuli to be eo infiltrated ? The answer is given in the comparison with the tests of Foraminifera, originally proposed by the writer, and illustrated in so conclusive a manner by the re- searches of Dr. Carpenter, 1 may add, in conclusion, that had geologists generally the oppor- tunity of studying Eozoon in situ, in good exposures, like that at St. lierre, they would much more fully understand and appreciate the arguments for its organic nature, than when they have had opportunities of examining only polished specimens and slicesf. Its * Trans. Koyal Irish Academy, 1871 3 1 / ■S-,s3rt.j-f».i3ir: Ko/(M»N C.VNADKNSK AT CUri: ST. I'IKItUK. 73 Strom.'itoporoid massoH. prtijcctinij; from tlic wcutliorod beds of liim*- Htono, wuuld at once utlruct the atteritiuii t)f any collector; mid the whole conditionH of its occurrence, whether entire or in frnj^ments, are precisely those of fossil corals in the Silurian liniestoneH. Fur- ther, the syinnietry and uniformity of its habit of {growth are much more apparent when they win be studied in large specimens prepared by natural weathering or by treatment with an acid. \ Note (Oct. liO). — Messrs. Itichardson and Weston, of the Gecdo- gical Survey, have recently revisited the locality of Eozuou at Cote St. Pierre mentioned in the above paper, and have cidlected some additional spooimons. One of these deserves notice, as illustrating the nalur(M)f Atrha'oxjthtfrimf. It is a small or young small speci- Fi{;M. ] -\.,~~SnifiIl irfiotlutril Sprcime)! of VW/.onu fnmi Piiite Fig. 1. Katural size; showing goiuTal loriii, and nwrvuJiiie portion abuvo and laminated portion bolow. 2. Enlarged casts of cells from upper part. ?>. Enlarged casts of cells from the lower part of the acervuliue portion. 4. Casts of sarcode layers from the laminatetl part ; enlarged. men, of a flattened oval form, 2| inches in its greatest diameter, and of no great thickness (fig. 1 ). It is a perfect cast in serpentine, and completely weathered out of the matrix, except a small portion of the upper surface, which was covered with limestone which I have carefully removed with a dilute acid. The sorpentinous casts of the I 74 .(. W. DAWSOX ON TIIK OCCUKKKNCE OK chambers arc in the lower part rcf^u^uiiy laminated ; but they arc remarkable for their finely mamiiullated a^jpearunce, arising from their division into innumerable ccmnected chamberlet8 rescmbUng those oi Archfosplmrina (fig, 4). In the upper part the structure be- comes acer\'uline, and the chamberlets rise into irregular prominences, which in the recent state must have been extremely friable, and, if brokjii up and scattered over the surfaces of beds, would not be distinguishable from the ordinary Anlutosphcenna'. This s])ecimen thus gives further probability to the view that the Atrhc^oxphnrincB may be for the most part detached chamberlets of Eozoon, pcrha])8 dispersed in a living state and capable of acting as germs. j V;, EXrLAXATlON OF . \TE X. Pig. 1. Fragments of skeleton of Eozoon, imbedded in dolomite limestone. («) Fragment with Oitnals. {!>) Fragments not sliowing canals. ('•) f)ol()mito. (Magnilied lU diameters.) 2. Laminated A'(ow'«, with veinot' eiirvsotile. («) Calcarotais wall, slightly eroded with aeid. {h) .Serpentine fdling ehambers. («•) Chrysotire \ein crossing the struetiires. (U) diam.) ,'{. I'ortion of a speeimens imilar to that in (ig. L' ; a very thin slice more highly magnified, {u) intermediate skeleton with portions of two large canals, {a) Troper-all with fine tiibiilation. {h) Serpentine filling chaml>ers. (') Chrvsiotile vein traversing seri)eutine. (Magnified •.If) diam.) 4. Small ArcfKrosp/iffriiia, .showing tubulated wall. ('J(X) diam.) ."), (), 7, H. Archceotiphxerimc, earils, as opaque objects, of some of the varieties. (7") diau\.) and 10. Similar specimens seen in section. (7.") diam.) The sjjeeimen rei)r(-sented in fig. 4 is from Long Lake ; all the others are from Petite Nation. i)l.SCL'!SSJU.\. Trof. l)cNC.\N said that ho thought the author had run the mine- ndogists rather bard. Fur his own part, when he first examined specimens of Enzovn he had coiiio to the conclusion that they were ancient Foraminifera with Xiunmuline peculiarities; and since he had actpiircd a more intimate ac(piaintaiice with fibrous minerals and serpentines, he found himself more than ever confirmed in this view. The discovery of isolated masses was verv interesting- seein-- that, Avhcther they were separated fragments or distinct organisms'' they still showed the Nnmmidine structure. Prof Duncan com- pared the habit of groAvth of Eozoon to that of the Xullipores, and suggested that It would be more philosophical to refer both the latter and the loraranuf'ora to lliickcl's grouj) •' JVotista " Mr. Ktuf.iudgh renu-vrkwl upon tl,e singular fact that whilst, as a general rule, we were disa,,pomted in ol)taining instructive sec- tions of Aoroo. Me had only to go to Dr. ('ari.cnfer to see sections which seemed to be convincing. He thotighf the difference of thes^cai,e;itubu,iand.oio:r'it^i:;::;'i^inr from Jersey sikocnnons which al the tirvl oi.,,,,,,. u, \ 'txtniu "•^i glance tic ffaid were like EOZOON CANADESSE AT cGlE ST. PIERRE. 75 "' ""VlikoTot : «S Ippcaranee, Lt Sir W. I^gan on I'rof. llAMSAY said that he ^^f f ^^^^ '" ,,, por his own part been formed, unless it 7' «/ XoomTto hin,, one of the most Mr. KVANS remarked that, it so^""-"/." . ^^ indication (he interesting points of th«,PJ[J"™';*;tn" of possibly separate believed, for the hrst time) of the <'?,™"''™^ \i J,^ » close organisms associated wth teoon. ^^^^^^J^he conditions of ui t i./Ou:':i ivieol .Do >> V V i ^ V/ V.kl i Kl E'.'ZOON an: Hii.'r-FtLER:N/E IT