FAUNA OF THE TRENTON GROUP. 
21 
Genus, Rafinesquima Hall and Clarke. 
Bafinesquina camerata (Conrad). 
Plate VI, figures 12, 13; Plate VII, figure 2. 
Strophomena camerata Conrad. Jour. Acad. Sc., Philadelphia, 8, 
1842, p. 254, PI. 14, fig. 5. Emmons, Am. Geol., 1, pt. 2, 1855, 
p. 197. 
Leptwna camerata Hall. Pal. New York, 1, 1847, p. 106, PI. 31A, 
figs. 2a, b. 
It is difficult to see why this quite distinct species has been united 
with Bafinesquina deltoidea . The outline of the shell is much less 
triangular, the convexity is much more even, the highest point being 
near the middle of the shell, and there is no abrupt geniculation. The 
interior is covered with small papillae, thus producing a very punc- 
tate appearance in natural casts or in partly exfoliated shells, as 
in Hall's figure. This is not seen in B. deltoidea. Conrad, in his 
figure, shows the hinge line much less than the greatest width, but as 
his illustration is a perspective drawing, exact proportions are not to 
be expected. Hall figured the specimen which he considered to be 
Conrad’s type and it has the same proportions as the shell here 
referred to this species. Many of the specimens have faint concentric 
wrinkles, especially near the hinge. 
A moderate-sized specimen has a width on the hinge of 22 mm. 
and length of 20' >5 mm.; a large specimen is 29 mm. wide at the hinge, 
and 26 mm. long. 
This species has to some extent the shape and form of Bafines- 
quina minnesotensis, but the muscle-scars do not cover so large an 
area, and the interiors of the shells are strongly pustulose. 
Horizon and Locality . This species was originally based upon a 
“specimen found by Mr. Yanuxem in New York,” Hall gives the 
locality without hesitation as Trenton Falls, but does not state any 
reason. The writer has not seen it at that locality. 
In Canada, Mr. Whittaker collected specimens near the top of the 
Trenton (Upper Cobourg) at Wellington, Prince Edward county. 
Out., and W. A. Johnston obtained' several at the same horizon on the 
northwestern corner of Georgina island, lake Simcoe. The species is, 
however, most; abundant in the Collingwood, both at Collingwood, 
S ncoe county, and Ottawa. 
