214 TRANSACTIONS OF THE CANADIAN INSTITUTE. [YOL. I. 



laminm sometimes cause such appearance." Mr. Winchell (without a 

 word of remark on this curiously amorphous name) further notes: " Rock 

 828, cherty concretions, producing BatracJioides nidificansr 



We may, perhaps, suppose the elder Hitchcock meant depressions which 

 resemble those which are made by nesting frogs. I doubt the connec- 

 tion which Mr. A. Winchell traces between the concretions and the de- 

 pressions —if the concretions are the same as those of which this paper 

 treats — locally called "cannon-balls," but named by me PelotechtJien 

 balanoides — an acorn-shaped thing, grown in or from mud. 



The Animikie slates of the Thunder Bay district (Port Arthur) are 

 generally but little inclined from the horizontal bed of deposition. They 

 are often in thin laminm — several to the inch — and, save that they are 

 black, you might imagine them to be deposited in the same way as the 

 clays of Rosedale and other points just north of Toronto. Probably they 

 were sediments in a slowly subsiding sea-bottom, and have altogether 

 perhaps 10,000 feet of thickness in this quarter. I find, wherever you 

 seek for them, examples of the PelotecJitJien. These do not, according to 

 my observations, occur between lainincc, but, on the contrary, there is a 

 clean breaking off of the la3'ers where they touch the PelotecJithen, and it 

 breaks away from the strata as a whole — as if there were some shell 

 around it — quite smoothly. Where the miners drift past one )^ou can 

 often see it sticking out of the side of the tunnel. 



The uniformity of shape proves these things to be a growth ; they are 

 sometimes round like an orange, oftener ovoid, and they so often have a 

 slight protuberance on the upper side that I compare them rather to an 

 acorn than to an orange or an &%g. Their internal structure, too, proves 

 them a growth ; and to illustrate this I have had a small speci- 

 men sliced by a lapidary — which I beg leave to add to your museum. 

 You will see that there is a very regular layer of pyrites around the no- 

 dule — thickest at about Yz of an inch within its outer surface and shading 

 off with a regular decrease towards the centre. This pyritous ring I have 

 never failed to notice, though I have broken dozens of them. Comparing 

 them to an acorn, you might say the layer was between the shell and the 

 meat. I asked one of our members to give the section a proper exami- 

 nation by a petrological microscope, but, owing to the composition of the 

 material (precisely the same argillite as the surrounding strata), nothing 

 additional was learned. I submit that no mere mineral nodule would 

 attain the size of many of these spheroids, I should have thought this 

 growth ^ protospongia, except for the conditions under which it seems to 

 have lived, that is if it be a zoophyte. 



