LA MELLIBRANCHIA TA. 
457 
SCHIZODUS PATULUS, 11. Sp. 
PLATE LXIU, FIG. 20. 
In part Cardiomorpha rotunda, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 63, fig-s. 17-20. 
1883. 
Shell very large, broadly ovate; length one-fourth greater than the height. 
Basal margin broadly curving. Post-inferior extremity narrowly rounded ; 
margin above obliquely sub-truncate. Cardinal line short. Anterior end 
large, contracted below the beak and broadly rounded below. 
Valves moderately convex below, becoming gibbous in the middle. 
Beaks a little anterior to the centre, prominent and rising above the hinge¬ 
line. Umbonal slope not defined, its continuation indicated by an extension 
of the shell at the post-inferior angle. 
Surface marked by fine concentric striae which are obscurely preserved on 
the cast of the interior. 
The specimen described has a length of 60 mm. and a height of 45 mm. 
This species is distinguished by the sub-central position of the beaks, unde¬ 
fined umbonal ridge and flattened posterior end of the shell. 
Formation and locality. In the Chemung group near Tioga, Tioga county, Pa. 
SCHIZODUS EMINENS, 11. Sp. 
PLATE XCV, FIG. 28. 
Shell very large, obovate, sub-trigonal; length a little less than the height; 
basal margin regularly curved. Post-inferior extremity sub-angular. Pos¬ 
terior margin nearly vertically truncate. Cardinal line very short. Ante¬ 
rior end short, broadly curving into the basal margin without limitation. 
Valves moderately convex below, becoming gibbous in the middle and 
above. 
Beaks sub-central, prominent, rising a little above the hinge-line. Umbo- 
