276 
Aug. F. Foerste 
hinge unknown, and hence the generic reference is based merely 
upon the general appearance of the exterior of the shell. 
Locality. At the Trinucleus horizon, several hundred yards 
west of the railroad bridge, east of Pulaski, New York. The 
same form is found also at the eastern edge of Lorraine village 
and at the road crossing over the creek, two miles west of Worth- 
ville, in the same state. 
The original of Fig. 10 on plate II, since lost in the Dayton 
flood, was collected by Aug. F. Foerste, in 1912, on the Richelieu 
River, at Chambly, associated in the same rock fragment with 
Catazyga headi and Proetus. An impression of the same species 
from the same locality, numbered 8430, is preserved in the Vic- 
toria Memorial Museum at Ottawa, Canada. 
Modiolopsis faba, (Conrad) was figured by Emmons^ from the 
black irregular-bedded limestone at Watertown, New York, 
where it was said to be abundant. His figure most closely re- 
sembles Fig. 6a on plate 35, in vol. I, of the Paleontology of New 
York. In this volume the horizon is described as belonging to 
the concretionary layers of the Trenton limestone, at Watertown. 
This would place it in the basal Trenton. Compared with typi- 
cal Colpomya faba, the valves of Colpomya pusilla are relatively 
higher posteriorly and lower at the beak, owing to the stronger 
divergence of the basal margin from the cardinal outline, amount- 
ing frequently from 30 to 35 degrees. The beak projects more 
distinctly above the cardinal margin, and the cardinal part of 
the anterior margin rises more nearly to the level of the straight 
cardinal outline of the shell posterior to the beak. The mesial 
sinus begins at the beak as a depression near the middle of the 
umbones; it tends to be more oblique than in Colpomya faba, 
but, as a matter of fact, the Lorraine form is scarcely distinguish- 
able from the Trenton types. 
The Lorraine form was figured by Hall from casts in the sand- 
stone layers forming part of the section at Pulaski, New York. 
The specimen represented by Fig. 4a on plate 82 of vol, I, of the 
Paleontology of New York, forms No. 736-4, in the American 
Museum of Natural History. Fig. 46, on the same plate, un- 
questionably represents the same species, although the original 
of this figure has been lost. ^ 
® Geological Report, New York, 1842, p. Fig. 5. 
