1368. J DAWSON — EOZOON CANADENSE. 317 



dendritic minerals,* more especially as Dr. Carpenter has already 

 shown their inaccuracy in many important points. I think, how- 

 ever, that it may serve a useful purpose shortly to point out the 

 more essential respects in which this comparison fails with regard 

 to the Canadian specimens — with the view of relieving the discus- 

 sion from matters irrelevant to it, and of fixing more exactly the 

 limits of crystalline and organic forms in the serpentine-limestones 

 and similar rocks. 



The fundamental error of Messrs. King and Rowney arises from 

 defective observation — in failing to distinguish, in the Canadian 

 limestones themselves, between organic and crystalline forms. 

 This is naturally followed by the identification of all these forms, 

 whether mineral or organic, with a variety of purely crystalline 

 arrangements occurring in other rocks, leading to their attaching 

 the term ' Eozoonal ' to any rock which shows any of the charac- 

 ters, whether mineral or organic, thus arbitrarily attached to the 

 Canadian Eozoon. This is obviously a process by which the 

 structure of any fossil might be proved to be a mere lusus naturce. 



A notable illustration of this is afforded by their regarding the 

 veins of fibrous serpentine, or chrysotile, which occur in the Cana- 

 dian specimens, as identical with the tubulated cell-wall of Eozoon 

 — although they admit that these veins traverse all the structures 

 indifferently and do not conform to the walls of the chambers. 

 But any microscopist who possesses specimens of Eozoon contain- 

 ing these chrysotile veins may readily satisfy himself that, under 

 a high power, they resolve themselves into prismatic crystals in 

 immediate contact with each other; whereas, under a similar 

 power, the true cell-wall is seen to consist of slender, undulating, 

 rounded threads of serpentine, penetrating a matrix of carbonate 

 of lime. Under polarized light, more especially, the difference is 

 conspicuously apparent. It is true that, in many specimens and 

 parts of specimens, the cell-wall of Eozoon is badly preserved and 

 fails to show its structure ; but in no instance does it present the 

 appearance of chrysotile, or of any other fibrous mineral, when 

 examined with care under sufficiently high powers. In my original 

 examination of Sir William Logan's specimens from Grenville and 

 the Calumet, I did not detect the finely tubulated cell-wall, which 

 is very imperfectly preserved in those specimens ; but the veins of 



* I do not include here the ' septariiform ? structure referred to above, 

 which is common in the Canadian serpentine and has no connexion with 

 the forms of the chambers. 



