LAMELLIBR AN CHI A TA. 
459 
This species resembles S. contractus of the Hamilton group, but is a larger 
shell, and differs in the more direct umbonal ridge, less gibbous valves, and in 
the absence of a sinuosity in the posterior margin. 
Formation and locality. In the Waverly sandstone, at Granville, Licking- 
county, 0. 
SCHIZODUS .ZEQUALIS, 11. Sp. 
PLATE LXXV, PIG. 35; and PLATE XCV, FIG. 29. 
In part Cythemdon (Sckizodus) quadrangularis. Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: 
PI. 75, tigs. 31-36 (35 in error). 18S3. 
Shell large, obovate; body of the shell sub-triangular; length a little greater 
than the height; basal margin regularly curved. Post-inferior extremity 
very slightly produced. Posterior margin somewhat vertically truncate. 
Cardinal line short. Anterior end large, contracted beneath the beak and 
broadly rounded below. 
Valves gently convex below, becoming moderately gibbous in the middle. 
Beaks sub-central, elevated, rising considerably above the hinge-line. 
Umbonal slope obtusely sub-angular, extending to the post-inferior extrem¬ 
ity. Post-cardinal slope rather wide, gently concave. 
Surface marked by fine concentric strife, which are partially preserved on 
the nearly smooth casts. 
A large specimen has a length of 52 mm. and a height of 45 mm. 
This species bears considerable resemblance to S. Chemungensis, var. quadran¬ 
gularis , but the base is more broadly rounded, and the anterior portion is more 
expanded below, giving the shell a more equilateral appearance. 
Formation and locality. In the Waverly sandstone, at Granville, Licking 
county, 0. 
