6 
MUSEUM BULLETIN NO. 20. 
compressed ; apex sub-central ; pedicle groove narrow, extending 
about one-half the distance or less from the apex to the margin 
of the shell; lamellae erect and numbering seventeen to twenty 
in the average specimen. 
These specimens are less than one-half the size of specimens 
from Arisaig, N.S. The latter specimens are also much more 
convex and tend to have a more elliptical outline and coarser lamel- 
lae, the number of which are about the same as in the specimens 
here described. The Arisaig specimens occur in limestone and 
it is thought that the differences between them and the above 
may be due to habitat, and in part to pressure. 
Or this} near tenuidens Hall. 
Plate I, figure 6. 
Small, averaging about 7 mm. wide and 4-5 mm. long. 
Hinge line straight, nearly as long as the width of the shell. 
Brachial valve somewhat concave, with a slight median depres- 
sion and probably a slight convexity near the beak. Plications 
rounded; incurved from the cardinal angles; increasing by im- 
plantation; number about 40. Pedicle valve convex. Char- 
acters poorly preserved in material at hand. 
This species appears to be very near if not identical with 
Hall’s 0. tenuidens from the Clinton of Oneida county, N.Y. 
Camarotoechia whitei (Hall) ? 
The presence of this species is based on one badly crushed 
specimen. Its size, shape, and characters of plications all point 
to this being the same as Hall’s species from the Niagara of New 
York. 
Spirifer radiatus Sowerby ? 
Plate II, figure 1. 
The specimens referred to this species are casts of interiors 
of pedicle valves and are small, the largest being less than 10 mm. 
in length. The casts show clearly the impressions made by 
the long dental plates. 
