Principal .F. \V. Dawson aw Eozoon canadense. .'Jl 



is possilde tliat he may not have read the elaborate reports of 

 Sir W. E. Lop;an and his assistants on the Laurentian rocks, 

 or even the descriptions of the beds containing Eozoon given 

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

 want of acijuaintance with the actual facts as to the inclusion 

 of the masses and fragments of Eozoon in regularlv 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 oi 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 ^o^ooh, j)resent no 

 indications of any such expansion as woidd have resulted from 

 the conversion of olivine into serpentine. This one considera- 

 tion miglit indeed close our case with reference to Halm's 

 hy])othesis, were there not some points of interest in his 

 further statements. 



3. Associated ^fineral<f. — 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 Avere 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 Avere 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 o^ Eozoon, and the replies to opponents, 

 without perceiving that large series of facts bearing on the 

 texture and microscopieal characters of the serpentine, calcite. 

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

 dite, spinel, and other mineral substances associated with Eozoo7i 

 had been accumulated and recorded. Many of these facts, 

 indeed, seem entirely to have esca])ed his attention. I may 

 instance the occuiTcnce of crystals of mica in the specimens 

 of Eozoon, this being by far the most common accidental 

 mineral present. Periiaps 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 tossiliferous 

 rocks. I have observed it in connexion with Halysites and 

 Crinoids in the schists of the White Mountains, and with 

 similar fossils of Upper Silurian age in the slates of Lake 

 ^lemphramagog and the New-Canaan district in Nova Scotia. 

 A still more strange omission is that of the Dolomite which 



