LAMELLIBRANCHIATA 
OF TIIE 
UPPER IIELDERBERG, HAMILTON, PORTAGE AND CHEMUNG GROUPS. 
II. 
DESCRIPTIONS OF SPECIES. 
MODIOMORPHA, Hall. 1870. 
Modiomorpha Schoharie. 
PLATE XXXIV, FIG. 13 ; AND PLATE XXXV, FIG. 11. 
Modiomorpha Schoharie, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PL 34, fig-. 13. 1883. 
Shell large, general form ovate, narrow in front; length one-third greater 
than the height; ventral margin broadly curved ; posterior margin abruptly 
rounded. Anterior end obliquely truncate above, abruptly rounded below. 
Hinge-line oblique, equal to two-thirds the height of the shell. 
Beaks oblique, situated on the anterior fourth of the shell, depressed, rising 
very slightly above the hinge. Umbonal region depressed convex. 
Test marked by strong, irregular, lamellose strise of growth, which are 
stronger on the anterior end and pallial margins. 
The muscular impressions are well-defined in the cast of the interior. 
The anterior adductor is the smaller and situated in the lower portion of the 
anterior end of the valve. The posterior adductor is sub-circular and located 
in the lower portion of the post-umbonal slope. Pallial line deeply impres¬ 
sed, following near to the ventral margin of the valve. 
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