CONTEMPORAraES OF EOZOON 203 



pended on circumstances. In some specimens there 

 are only a few regular layers, and then a heap of 

 irregular cells. In other cases a hundred or more 

 regular layers were formed ; but even in this case 

 little groups of irregular cells occurred at certain 

 points near the surface. I have also found some 

 masses clearly not fragmental which consist alto- 

 gether of acervuline cells. A specimen of this kind 

 is represented in Fig. 52. It is oval in outline, 

 enclosed in a nodule of serpentine, about three 

 inches in length, wholly made up of rounded or 

 cylindrical cells, the walls of which have a beau- 

 tiful tubular structure, but there is little or no 

 supplemental skeleton. Whether this is a portion 

 accidentally broken off from the top of a mass of 

 Eozoon, or a peculiar varietal form, or a distinct 

 species, it would be difficult to determine. In the 

 meantime I have described it as a variety, " acervu- 

 lina" of the species Eozoon Canadense. It admits 

 of comparison with a fragment figured by Dr. 

 Carpenter, which he compares with the chamberlets 

 and tubes of Nummiilites Icevigata of the Eocene.^ 

 Another variety also, from Petite Nation, shows 



* Proceedings of Geological Society ^ 1875. 



