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GEOLOGY OF THE FOURTH DISTRICT. 
Among the Brachiopoda, the following have been selected as most characteristic of the 
group, though there are other species, perhaps, equally numerous. 
120 . 
1. Strophomena nervosa. 3. Strophomena arctostriata. 5 a, b, c. Strophomena interstrialis. 
2. Strophomena bifurcata. 4. Strophomena pectinacea. 
1. Strophomena nervosa, n. s. — Semicircular, with the hinge line greatly extended, forming 
a spine-like prolongation; surface marked by undulating, nerve-like striae, which augment in 
number toward the margin, and between which are finer striae. 
1 a. An enlarged portion of the shell. The shell resembles the nerved wings of some 
insects, which with the greatly extended hinge line is sufficient to distinguish it. 
Localities —Bath ; Campbelltown. 
2. Strophomena bifurcata, n. s. — Broadly semi-elliptical; hinge line extended beyond the 
width of the shell, and angulated at the extremities ; surface marked by about 34 to 36 ribs 
at the hinge, which uniformly and regularly bifurcate once or twice before reaching the margin. 
This is a widely distributed fossil of the Chemung, extending over 150 miles in an east and 
west direction. 
Localities —Napoli, Cattaraugus county; Chemung. 
3. Strophomena arctostriata, n. s. — Broadly semi-elliptical or semicircular; lower valve 
very convex, slightly impressed in front; hinge line scarcely extending beyond the width of 
the shell; surface covered with numerous, crowded, unequal striae. 
Localities —Hobbieville ; Chemung. 
4. Strophomena pectinacea, n. s. — Semi-oval; lower valve very convex ; hinge line shorter 
than the greatest width of the shell; surface marked by from 24 to 28 prominent sharp striae, 
with two or three intermediate ones which are less prominent. 
This fossil somewhat resembles the next species, but the striae are more prominent and 
fewer in number. It is a widely distributed fossil in this group. 
Localities —Hobbieville ; Rockville ; Cattaraugus county. 
