LAMELLIBRANCHJA TA. 
500 
nearly straight, abruptly recurving at the posterior extremity, which is 
almost vertically truncate. Cardinal line straight, scarcely declining poste¬ 
riorly. Anterior end short and abruptly rounded below. 
Yalves regularly convex below, becoming gibbous in the middle and above. 
Beaks near the anterior third, incurved and rising hut little above the 
hinge-line. Umbonal slope obtusely angular, extending to the post-inferior 
extremity. 
Surface marked by fine concentric striae, which become fasciculate and are 
elevated into somewhat irregular concentric undulations, which extend from 
near the anterior end over the umbonal slope. Interior unknown. 
Two specimens measure respectively 24 and 22 mm. in length, and 13 and 
13 mm. in height. 
Formation and localities. In the arenaceous shales of the Chemung group, at 
Connewango, Cattaraugus county, and Cherry Creek, Chautauqua county, N. Y. 
PROTOMYA, n. g. 
Protomya oblonga. 
PLATE LXIII, FIG. 21. 
Cardiomorpha oblonga, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 63, tig-. 21. 1883. 
Shell large, elongate-ovate, narrower behind; length twice the height; basal 
margin very gently curving. Posterior extremity gaping, regularly rounded. 
Cardinal line gently declining posteriorly. Anterior end large, rounded. 
Valves moderately and regularly convex. 
Beaks a little anterior to the middle of the length, low, not strongly de¬ 
fined, rising but little above the hinge-line. Umbonal slope regularly con¬ 
vex, not defined. 
Surface, in the cast, marked by fine concentric striae, which are aggregated 
into fascicles, producing low undulations of the surface. 
Anterior muscular imjiression strongly marked, situated just within the 
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