300 
Aug. F. Foerste 
preserved in the Paleontological collection, Canadian Geological 
Survey, Victoria Memorial Museum, Ottawa, Canada. No. 8420. 
This species was named, but not described or figured, by Billings. 
33. Whitella complanata, sp. nov. 
{Plate I, Fig. 2) 
Shell originally probably very oblique, with a relatively short 
hinge-line and anterior margin, and a long basal margin, but at 
present strongly compressed toward the beak, decreasing the orig- 
inal convexity of the shell, especially along the umbonal areas, 
and somewhat obscuring the character of its original outline to 
the beak. Length of the shell along the umbonal ridge, from the 
beak to the lower posterior margin, 60 mm. ; greatest length from 
front to rear, parallel to the basal margin, 58 mm.; diameter 
transverse to the latter measurement, 36 mm.; convexity of the 
single valve in its present compressed condition 10 mm., originally 
possibly 15 mm.; hinge-line posterior to the beak at least 20 mm., 
possibly 25 mm. in length. Umbonal ridge forming an angle of 
about 45 or 50 degrees with the hinge-line, as far as can be deter- 
mined from the present condition of the specimen. It is quite evi- 
dent that the umbonal ridge never was conspicuously developed, 
its convexity being only slightly greater than that of the remainder 
of the shell, and it never was angular, even near the beak. The 
beak apparently was broad and the anterior margin extended but 
moderately beyond the beak. The nearly straight basal margin 
rounds rather rapidly into the moderately convex posterior margin, 
the two forming, in a general way, an angle of about 60 degrees. 
It is evident from the growth lines that this angle becomes more 
acute with age, and that the length along the umbonal ridge 
increases more rapidly than any other dimension. 
Type. Bearing two labels. One of these is: Modiolopsis com- 
planata, Riviere des Hurons, Hudson River group, James Richard- 
son; and the other: Richelieu River, Chambly v. 8. The two 
localities are by no means identical. In the Geology of Canada 
'published in 1863, this species is listed from the Riviere des 
Hurons. Lithologically, the rock might come from either locality. 
On the rear of the type specimen, Lyrodesma poststriatum is 
present. The type, numbered 8421, is preserved in the Victoria 
Memorial Museum, Ottawa, Canada. It was named but not 
described or figured, by Billings. 
