Principal J. W. Dawson on Eozoon canadense. 31 



is possible that he may not have read the elaborate reports of 

 Sir W. E. Logan and his assistants on the Laurentian rocks, 

 or even the descriptions of the beds containing Eozoon given 

 bj Logan, Hunt, and myself. In any case, the question shows 

 want of acquaintance with the actual facts as to the inclusion 

 of the masses and fragments of Eozoon in regularly bedded 

 limestones which contain also nodules and layers of serpentine. 

 Had these facts been clearly before his mind, he would pro- 

 bably have adopted some other theory of the origin of Eozoon ^ 

 since it seems physically impossible that regularly bedded and 

 laminated limestones can have suffered such changes as he 

 supposes. The bands and nodules and grains of serpentine, 

 whether with or without the structure of Eozoon, present no 

 indications of any such expansion as would have resulted from 

 the conversion of olivine into serpentine. This one considera- 

 tion might indeed close our case with reference to Hahn's 

 hypothesis, were there not some points of interest in his 

 further statements. 



3. Associated Minerals. — He seems to be unaware of the 

 elaborate series of microscopic examinations to which I sub- 

 jected the limestones containing Eozoon, and many others more 

 or less resembling them, before the specimens were submitted 

 to Dr. Carpenter. These researches were made with the best 

 instruments, with large series of specimens prepared in the 

 best manner by Mr. Weston, of the Geological Survey, and 

 with the experience of twenty years in observations of this 

 kind, and were aided by the unsurpassed chemical skill of 

 Dr. Sterry Hunt. The whole of the results have not, it is 

 true, been published in detail. Yet he cannot have read the 

 published descriptions oi Eozoon, and the replies to opponents, 

 without perceiving that large series of facts bearing on the 

 texture and microscopical characters of the serpentine, calcite, 

 Dolomite, Loganite, mica, pyroxene, graphite, pyrite, cbondro- 

 dite, spinel, and other mineral substances associated vfit\\ Eozoon 

 had been accumulated and recorded. Many of these facts, 

 indeed, seem entirely to have escaped his attention. I may 

 instance the occurrence of crystals of mica in the specimens 

 of Eozoon, this being by far the most common accidental 

 mineral present. Perhaps he has confounded its crystals with 

 aragonite and olivine. It is to be observed here that mica is 

 one of the most usual minerals developed in altered fossiliferous 

 rocks. I have observed it in connexion with Halysites and 

 Crinoids in the schists of the White Mountains, and Avith 

 similar fossils of Upper Silurian age in the slates of Lake 

 Memphramagog and the New-Canaan district in Nova Scotia. 

 A still more strange omission is that of the Dolomite which 



