92 Trans. Acad. Sci. of St. Louis. 



Remarks. This species has often been confused with G. 

 hannibalensis, but it differs from that species in its much 

 greater gibbosity, and in its more anterior beaks. The spe- 

 cies exhibits a good deal of variation in its proportions and 

 general outline. In some specimens the truncation of the 

 posterior margin is much more pronounced than in the speci- 

 men illustrated, and the ventral margin may be much more 

 strongly curved. 



Grammysia amygdalinus (Win.). 



PI. IV.f.16. 



Olossites amygdalinus (in part"). Bull. IT. S. G. S. No. 153: 289. 



Shell moderately convex, 24 mm. long and 11 mm. high. 

 Hinge-line long, arcuate ; anterior margin rather abruptly 

 rounded ; ventral margin nearly straight in the middle, gently 

 curving upward towards each extremity ; posterior margin 

 arcuate, oblique, meeting both the cardinal margin above and 

 the ventral margin below in rounded angles. Beak situated 

 about one-fourth the length of the shell from the anterior 

 extremity, elevated above the hinge-line, somewhat flattened, 

 incurved and pointed forward. An obtusely subangular or 

 rounded umbonal ridge extends from the beak to the postero- 

 ventral angle. Posterior to the beak, just below the dorsal 

 margin and parallel with it, there is a groove-like depression 

 which gives to the cardinal margin an angular, ridge-like 

 appearance, the upper slope of which is sharply inflected. 

 Anterior to the beak on the dorsal margin, there is a deep 

 lunette. Surface marked by strong concentric wrinkles which 

 are more conspicuous towards the ventral and posterior mar- 

 gins. A broad, shallow, ill-defined sinus or mere flattening of 

 the shell runs from the beak to a point in front of the middle 

 of the ventral margin. 



Remarks. Five specimens in the University of Michigan 

 collection are attached to the card marked "Types" and 

 bearing the label of this species. Three of these specimens 

 are quite distinct from the other two, and are evidently mem- 

 bers not only of a distinct species but of another genus as 

 well. Winchell's description and the dimensions given by 

 him, agree with one of the two specimens which are distinct 



