THE PEESEEVATION OP EOZOON. 113 



able rocks containing Eozoon, such, things occur in the 

 more highly crystalline parts of the limestones, and 

 ^ven in some still showing traces of the fossil. We 

 id many disseminated crystals of magnetite, pyrite, 

 ^pinel, mica, and other minerals, curiously curved 

 prisms of vermicular mica, bundles of aciculi of tre- 

 lolite and similar substances, veins of calcite and cry- 

 )lite or fibrous serpentine, which often traverse the 

 )est specimens. Where these occur abundantly we 

 isually find no organic structures remaining, or if 

 ley exist they are in a very defective state of preser- 

 ition. Even in specimens presenting the lamination 

 Eozoon to the naked eye, these crystalline actions 

 have often destroyed the minute structure ; and I fear 

 that some microscopists have been victimised by 

 having under their consideration only specimens in 

 which the actual characters had been too much de- 

 faced to be discernible. I must here state that I have 

 found some of the specimens sold under the name of 

 Eozoon Canadense by dealers in microscopical objects 

 to be almost or quite worthless, being destitute of 

 any good structure, and often merely pieces of Lauren- 

 tian limestone with serpentine grains only. I fear 

 Jihat the circulation of such specimens has done much 

 cause scepticism as to the Foraminiferal nature of 

 3ozoon. No mistake can be greater than to suppose 

 lat any and every specimen of Laurentian limestone 

 lust contain Eozoon. More especially have I hitherto 

 died to detect traces of it in those carbonaceous or 

 ^graphitic limestones which are so very abundant in 



