LAMELLIBRANCHIA TA . 
85 
Crenipecten glaber. 
PLATE IX, FIGS. 20, 22? 
Lima glaber, Hall. Geolog. Surv. N. Y. : Rep. Fourth Dist., p. 255. 1843. 
Crenipecten glaber, Hall. Pal. N. Y, vol. v, pt. 1. Plates and Explanations: PI. 9, figs. 20, 22? 
Jan., 1883. 
Shell small, ovate, erect, very slightly oblique; height about one-fifth greater 
than the length; pallial margins regularly rounded, more extended on the 
posterior side. 
Left valve moderately convex above, and depressed-convex below. Right 
valve unknown. 
Hinge-line straight, length equal to about one-half the length of the valve. 
Beak acute, erect, somewhat prominent, not elevated above the hinge. 
Umbonal region well defined by the sulci, subtending an acute angle. 
Ears triangular, nearly equal, separated from the body of the shell by 
shallow sulci; margins straight or slightly concave: posterior ear a little 
the larger. Byssal sinus not distinct. 
The cast is marked only by fine concentric striae. 
Interior unknown. 
The crenulations of the ligamental area are obscure in the specimen. 
The original of this species is 12 mm. in length, 16 mm. in height, and 
hinge-line 6 mm. 
This specimen is embedded vertically to the lines of rock bedding, and the 
proportions of length and height may have been changed. The species is 
known by its erect form, conspicuous ears and great comparative height. 
The specimen of figure 22 is referred with doubt to this species; the erect 
form is similar; the proportional length is slightly greater. 
Formation and localities. In shales of the Chemung group at Philipsburg and 
Rockville, Alleghany county, N. Y. 
