FOUND IX CANADIAN HOCKS WESTOX. 7 



It will be seen that each concretion has a radiating structure, 

 most of them show concentric layers. 



12. Pisolitic limestone (so-called from pisum a pea), has, so 

 far as I know, only been found in Canada in rounded pieces in the 

 conglomerates of the " Quebec Group." These contain many 

 fossils, which are supposed to belong to the Upper Cambrian 

 zone ; the pebbles belong to the same geological horizon. I 

 have found no radiating structure in any of these pisolite 

 forms ; but this peculiarity is seen in all sections of oolitic 

 limestone. Sections of pisolite limestone from St. Anne, Bic, 

 Point Levis, and other localities in the province of Quebec, show 

 -each concretion to be formed of concentric layers, in some cases 

 little or no nucleus is found, while in others the nuclei forms 

 three parts of the whole. 



FIG. 4. 



Fig. 4 shows several of the pisolitic forms cut through the 

 -centre. In the rock these little round balls are cemented 

 together with so little calcareous matter that a slight tap with 

 the hammer will detach them. 



13. In 1892 a piece of oolitic limestone, collected from the 

 'Trenton rocks of Ottawa by W. R. Billings, was sent me for 

 microscopic examination. Sections showed these minute con- 

 cretions to be precisely like those of the limestones of Cape 

 Breton and Arisaig. Fig. 3. 



14. A limestone from the lower carboniferous of New 

 Brunswick is partly made up of concretionary forms which, 

 when weathered, might readily be taken for small stromato- 

 porids, but which in thin slices under the microscope show a 

 nucleus of crystallized calcite and concentric rings, between 



