110 THE CANADIAN NATURALIST. [April 



and complexity, unexampled, in so far as yet known, in the succeed- 

 ing ages of the earth's history. This early culmination of the 

 Rhizopods is in accordance with one of the great laws of the 

 succession of living beings ascertained from the study of the 

 introduction and progress of other groups ; and, should it prove 

 that these great Protozoans were really the dominant type of 

 animals in the Laurentian period, this fact might be regarded as 

 an indication that in these ancient rocks we may actually have the 

 records of the first appearance of animal life on our planet. 



Since the above was written, thick slices of Eozoon from Gren- 

 villehave been prepared, and submitted to the action of hydrochloric 

 acid until the carbonate of lime was removed. The serpentine then 

 remains as a cast of the interior of the chambers, showing the 

 form of their original sarcode-contents. The minute tubuli are 

 found also to have been filled with a substance insoluble in the 

 acid, so that casts of these also remain in great perfection, and 

 allow their general distribution to be much better seen than in the 

 transparent slices previously prepared. These interesting prepara- 

 tions establish the following additional structural points : 



1. That the whole mass of sarcode throughout the organism was 

 continuous ; the apparently detached secondary chambers being, as 

 I. had previously suspected, connected with the larger chambers 

 by canals filled with sarcode. 



2. That some of the irregular portions without lamination are 

 not fragmentary, but due to the acervuline growth of the animal j 

 and that this irregularity has been produced in part by the formation 

 of projecting patches of supplementary skeleton, penetrated by 

 beautiful systems of tubuli. These groups of tubuli are in some 

 places very regular, and have in their axes cylinders of compact 

 calcareous matter. Some parts of the specimens present arrange- 

 ments of this kind as symmetrical as in any modern Foraminiferal 

 shell. 



3. That all except the very thinnest portions of the walls of the 

 chambers present traces, more or less distinct, of a tubular 

 structure. 



4. These facts place in more strong contrast the structure of the 

 regularly laminated specimens from Burgess, which do not show 

 tubuli, and that of the Grenville specimens, less regularly laminated 

 and tubulous throughout. I hesitate however to regard these two 

 as distinct species, in consequence of the intermediate characters 



