LAMELLIBRANCHIA TA. 
239 
Interior unknown. 
The specimen described has a length of 29 mm., height 16 mm., and hinge¬ 
line 31 mm. 
This species is much smaller than P. profundus , less elongate and less gibbous 
in its proportions. The beak is apparently more elevated and angular, but 
the angularity of the umbonal region is not continued along the body as in the 
preceding form. 
Formation and locality. In the shales of the Chemung group at Rockville, 
Alleghany county, N. Y. 
Pteeonites inoptatus, n. sp. 
PLATE LXXXVII, FIG. 5. 
Shell of medium size, broadly semi-ovate; body ovate, oblique, making an 
angle of about 25° with the cardinal line; ventral and basal margins broadly 
rounded; post-basal extremity abruptly recurved. 
Left valve regularly convex, slightly gibbous above. Right valve unknown. 
Hinge-line straight, less than the greatest length of the shell. 
Beak sub-anterior, directed forward, prominent and incurved over the 
cardinal line. Umbonal angle acute. 
Anterior end short, nasute; extremity acute. Wing very narrow-trian¬ 
gular, scarcely defined, joining the body at the posterior extremity; margin 
oblique, in direct continuation with the posterior extremity and curving 
backward just beneath the cardinal line; extremity acute. 
Test marked by concentric striae of growth which are strongly fasciculate 
on the anterior end and ventral margin. 
Interior unknown. 
The left valve described has a length of 38 mm., height 21 mm., and 
hinge-line 33 mm. 
This species is distinguished from the other forms of this genus by its narrow 
wing and shorter hinge-line. It has" the characteristic aspect of Pteronites 
although approaching, in several particulars, to some species of Leptodesma. 
Formation and locality. In the Chemung group, Mansfield, Tioga county, Pa. 
