I4I 
tion, Bordeaux, Outer Mile End, and Caughnawaga. 
As one follows the limestone westward beyond Hawkes- 
bury it becomes thinner, less fossiliferous, and less pure, 
and west of Ottawa it has not been reported. At Ottawa 
it still carries Camarotechia plena, but no cystid has been 
seen west of Rockland, which is 30 miles (48 km.) east 
of Ottawa. 
BLACK RIVER GROUP. 
Pamelia.—At Ottawa, the thin limestone of the upper 
Chazy is succeeded by a formation which is shaly and 
sandy in its lower’ portion, but consists. chiefly 
of limestone. There are two easily recognized divi- 
sions; a lower, composed of dark blue and gray limestone 
full of ostracods, with sandy shales at the base, and an upper 
consisting of light buff, fine-grained, pure limestone alter- 
nating with beds of bluish magnesian limestone, which 
weathers yellow. At the base of the upper division is a 
bed of coarse sandstone. Neither division contains a 
great variety of fossils, but such species as are found are 
more nearly akin to the Lowville and Black River faunas 
than to the Chazy. As this formation is traced eastward 
it becomes thinner. The last actual outcrop seen in that 
direction is at L’Original, and at Montreal the Lowville 
rests directly upon the limestone of the Aylmer formation. 
The principal fossils of the lower division are Bey- 
richia clavigera and other ostracods, Bathyurus acutus, 
and Helicotoma whiteavsiana. In the upper part Isochilina 
armata, Leperditia fabulites, Bathyurus superbus, Tetradium, 
and other fossils are found. 
Lowville—The Lowville is a thin formation, consisting 
mostly of buff, fine-grained, rather pure limestone, with 
an occasional shaly bed. It is characterized by a great 
abundance of Tetradium cellulosum; Bathyurus extans is 
also a typical fossil. Though only 15 to 30 feet (4:5 to 
9-I m.) thick, the Lowville is very persistent in this region, 
but disappears to the north-east, where it is absent from 
the section at Joliette, 50 miles (80-4 km.) north-east of 
Montreal. 
Black River.—This is another thin formation, consisting 
of thick beds of rather impure, gray to black limestone. 
The fauna is a large one, some of the more common and 
characteristic species being Columnaria halli, Hormoceras, 
