Principal J. W. Dawson on Eozoon canadense. 33 



formations in Canada referred by Sir William Logan to the 

 Quebec group, there occur serpentines enclosing and filling the 

 cavities of ordinary palaeozoic fossils. These serpentines were 

 mentioned in connexion with Eozoon in my early papers in 

 the ' Geological Journal,' because I had examined slices of them 

 in the course of my studies of the Laurentian specimens ; but 

 much larger series of slices, prepared by Mr. Weston to illus- 

 trate Sir William Logan's later researches in these rocks (un- 

 happily left unfinished at the time of his death), have recently 

 been placed in my hands. In specimens of ophiolite from 

 Melbourne I find the dark green serpentine of that locality 

 not only enveloping fragments of shells, Crinoids, and corals, 

 but penetrating their pores and cavities. In another specimen 

 collected by Mr. Richardson at Le Chibogomon, in a great 

 bed of olive-green serpentine, which has been analyzed by 

 Hunt, there is a specimen of a tabulate coral quite large enough 

 to be seen distinctly with the naked eye, having many of its 

 thin-walled hexagonal cells filled with serpentine, while others 

 are filled with calcite. These facts, of which I hope details 

 will shortly be published, effectually dispose of Halm's diffi- 

 culties as to serpentine filling the cavities of fossils, 



I may add that the question whether chondrodite (which 

 does occur in the Laurentian limestones) may have been a 

 som'ce of serpentine has been discussed by Dr. Hunt, and 

 answered in the negative, and that Giimbel has found un- 

 altered chondrodite filling cavities of Eozoon'^. Some of these 

 points in relation to the Laurentian serpentines of Canada 

 have been fully discussed by Dr. Hunt as far back as 1853, 

 in his memoir on the Constitution of Mineral Species, in 

 Silliman's Journal for that year. 



5. The Lamince of Eozoon. — Halm says that " the calca- 

 reous layers occur in serpentine rocks which contain no Eozoon 

 canadense^ This of course no one denies ; but its terms 

 betray a curious misconception. In the case of Eozoon it is 

 the serpentine layers that are included in the limestone, not 

 the limestone in the serpentine. Further, the serpentine layers 

 are limited to certain definite forms, and have no more re- 

 semblance to ordinary rock-lamination than have the layers of 

 Stromatoporce or fossil trunks of trees. I have examined 

 numerous laminated serpentines and ophiolites, as well as 

 laminated rocks and concretions of other kinds, some of which 

 have indeed been sent to me for examination by collectors, who 

 supposed that they might be allied to Eozoon ; but I have 

 not, even in the case of small fragments, experienced any 



* Memoir on Laureutiau Rocks of Bav.iria. ISOi!. 

 Ann. d' Mag. N. Hist. Ser. 4. Vol. xviii. 3 



