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



BemarJcs. This species has often been confused with G. 

 hannihalensis, 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.). 



PL IV. f. 16. 



Olossites amygdalinus (in part). Bull. U. 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 



