58 PKOCEEDINGS OF THE GEOIOGICAI SOCIETY. [NoV. 23, 



in point of magnitude and complexity, unexampled, in so far as yet 

 known, in the succeeding ages of the earth's history. This early 

 culmination of the Ehizopods 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 indica- 

 tion 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 Grenville 

 have been prepared, and submitted to the action of hydrochloric acid 

 until the carbonate of lime was removed. The serpentine then re- 

 mains 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 preparations 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 ; 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 

 sheU. 



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 as 

 distinct species, in consequence of the intermediate characters pre- 

 sented by specimens from the Calumet, which are regularly laminated 

 like those of Burgess, and tubulous like those of Grenville. It is pos- 

 sible that in the Burgess specimens tubuli originally present have 

 been obhterated ; and in organisms of this grade, more or less altered 

 by the processes of fossilization, large suites of specimens should be 

 compared before attempting to establish specific distinctions. 



Some additional specimens, from a block consisting principally of 

 serpentine, differ from the ordinary Grenville specimens in the more 

 highly crystalline character of the calcareous spar and serpentine, in 

 the development of certain minute dendritic crystallizations, and in 

 the apparent compression and distortion of the fossils. These ap- 



