THE PRESEEVATION OP EOZOON. 113 



able rocks containing Eozoon, sucL. things occur in tlie 

 more highly crystalline parts of the limestones^ and 

 even in some still showing traces of the fossil. We 

 find many disseminated crystals of magnetite, pyrite, 

 spinel_, mica, and other minerals, curiously curved 

 prisms of vermicular mica, bundles of aciculi of tre- 

 molite and similar substances, veins of calcite and cry- 

 solite or fibrous serpentine, which often traverse the 

 best specimens. Where these occur abundantly we 

 usually find no organic structures remaining, or if 

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

 vation. Even in specimens presenting the lamination 

 of 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 

 that the circulation Of such specimens has done much 

 to cause scepticism as to the Foraminiferal nature of 

 Eozoon. No mistake can be greater than to suppose 

 that any and every specimen of Laurentian limestone 

 must contain Eozoon. More especially have I hitherto 

 failed to detect traces of it in those carbonaceous or 

 graphitic limestones which are so very abundant in 



