1865.] DAWSON — STRUCTURE OF EOZOON. 105 



coarser texture of the tubuli in the Laurentian specimens. It 

 accords well with the great dimensions of these, that they should 

 thus thicken their walls with an extensive deposit of tubulated cal- 

 careous matter ; and from the frequency of the bundles of tubuli, 

 as well as from the thickness of the partitions, I have no doubt that 

 all the successive walls, as they were formed, were thickened in this 

 manner, just as in so many of the higher genera of more modern 

 Foraminifera. 



It is proper to add that no spicules, or other structures indica- 

 ting affinity to the Sponges, have been detected in any of the 

 specimens. 



As it is convenient to have a name to designate these forms, 

 I would propose that of Eozoon, which will be specially appropriate 

 to what seems to be the characteristic fossil of a group of rocks 

 which must now be named Eozoic rather than Azoic. For the 

 species above described, the specific name of Canadense has been 

 proposed. It may be distinguished by the following characters : — 



Eozoon Canadense; gen. et spec. nov. 



General form. — Massive, in large sessile patches or irregular 

 cylinders, growing at the surface by the addition of successive 

 laminae. 



Internal structure. — Chambers large, flattened, irregular, with 

 numerous rounded extensions, and separated by walls of variable 

 thickness, which are penetrated by septal orifices irregularly 

 disposed. Thicker parts of the walls with bundles of fine branch- 

 ing tubuli. 



These characters refer specially to the specimens from Grenville 

 and the Calumet. There are others from Perth, C. W., 

 which show more regular laminae, and in which the tubuli have 

 not yet been observed ; and a specimen from Burgess, C. W., 

 contains some fragments of laminae which exhibit, on one side, 

 a series of fine parallel tubuli like those of Nummulina. These 

 specimens may indicate distinct species ; but on the other hand, 

 their peculiarities may depend on different states of preservation. 



With respect to this last point, it may be remarked that some of 



it would have been impossible satisfactorily to investigate the structure 

 and affinities of Eozoon. I have also to acknowledge the kindness of 

 Dr. Carpenter in furnishing me with specimens of some of the forms 

 described in his works. 



