LAMELLIBRANCHIA TA. 
271 
Modiomorpha putillus. 
PLATE XLI, FIGS. 1, 2. 
Modiomorpha putillus, Hall. Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 41, figs. 1, 2. 18S3. 
Shell small, sub-ovate, gibbous; height more than half the length; anterior 
margin abruptly rounded; base broadly curving. Anterior end convex, lim¬ 
ited by a broad depression extending backward from a point just anterior 
to the beak to the ventral margin. 
Valves very convex and obtusely sub-angular along the post-umbonal 
slope; the point of greatest convexity is a little anterior to the middle of 
the length of the shell. 
Hinge-line slightly oblique, somewhat longer than the height of the shell. 
Beaks prominent, curving down to the hinge-line. Umbonal region 
gibbous. 
Test not preserved. The internal mould shows traces of strong concentric 
laminae which probably marked the exterior shell. 
Anterior muscular impression comparatively large, situated close to the 
anterior margin. Pallial line strongly impressed. Other characters of the 
interior unknown. 
A specimen of normal form and preserving both valves has a length of 17 
mm., height 10.5 mm., and depth of both valves 9 mm. 
This species more nearly resembles M. neglcda of the Chemung group than 
any other, but may be distinguished by its narrower form and less oblique 
hinge-line. 
Formation and locality. In the Schoharie grit, Schoharie, N. Y. 
Modiomorpha (?) ponderosa. 
PLATE XXXIV, FIGS. 11, 12; and PLATE XXXV, FIG. 8. 
Sangiunolites ? ponderosus, Hall. Prelim. Notice Lamellibranchiata, 2, p. 35. 1870. 
Modiomorpha ponderosa, Hall. S. A. Miller, Cat. Amer. Pal. Foss., p. 196. 1877. 
“ “ “ Pal. N. Y., vol. v, pt. 1. Plates and Explanations: PI. 34, figs. 11, 12. 
1883. 
Shell large, rhomboid-ovate, gibbous; length one-third greater than the height; 
posterior margin broadly rounded; basal margin slightly concave toward 
