FOUND IN CANADIAN ROCKS—WESTON. 7 
It will be seen that each concretion has a radiating structure, 
and most of them show concentric layers. 
12. Pisolitic limestone (so-called from piswm a pea), has, so 
far as I know, only been found in Canada in rounded pieces in the 
conglomerates of the “Quebee 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 Quebee, 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 caleareous 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- 
eretions 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 
