NATURAL SCIENCES OP PHILADELPHIA. 73 



in that group until its relations can be more precisely determined 

 from the study of better specimens. 

 Locality and position. Same as last. 



GRAMMYSIA VENTRICOSA, Meek. 

 Shell attaining a moderate size, extremely ventricose, the con- 

 vexity being greater than the height, with the greatest gibbosity 

 a httle in front of and above the middle ; height equalling about 

 half the length ; posterior side comparatively long, a little crapin-. 

 and narrowly rounded in outline, at or a little above the middle"' 

 palhal margin usually a little sinuous near the middle or in front 

 of It; anterior side very short, concave just under the beaks to 

 the base of the lunule, where the margin is subangular or very 

 abruptly rounded and most prominent, while below this it rounds 

 obliquely backward into the base ; cardinal margins scarcely 

 more than equalling half the entire length of the valves and in- 

 flected so as to form a kind of shallow escutcheon; beaks very 

 gibbous, moderately elevated, oblique, strongly incurved, and 

 placed almost over the anterior margin ; lunule deep, ovate or 

 obovate, and well defined; posterior umbonal slopes prominently 

 rounded ; flanks without any oblique ridge or sulcus. Surface 

 marked on the anterior side of the valves near the lunule by small 

 wrinkles, which pass into mere lines and linear furrows of growth 

 farther back, while even the latter become nearly or quite obsolete 

 over the more gibbous parts of the valve. 



Length of largest specimen seen, 2.50 inches; height, 1.30 

 inches; convexity, 1.55 inches. 



I know nothing of the hinge or muscular and pallial impres- 

 sions of this shell, and refer it to Grammysia from its form and 

 general appearance. It shows no traces of the oblique ridge and 

 furrows seen on the typical species of that genus, but it Is well 

 known that this character is not constant in the group. 



Locality and position. Same as foreo-oino-, 



GASTEROPODA. 



PLATYCERAS MULTISPINOSTJM, Meek. 



Shell attaining a large size, comparatively thin, depressed sub- 

 ovate, and very oblique ; apex free, stout, obliquely coiled so as 



1871.J PART I. — 6 



