176 Annals of the Carnegie Museum. 



imperfect material, a brief survey of the principal characters of the 

 species of Raphistoma previously described from the Chazy will be 

 presented. 



Raphistoma striatum (Emmons). 

 Spire nearly flat, slightly elevated toward the apex ; ventricose 

 below ; outer margin obtusely angular. Aperture subtriangular, nearly 

 straight above and rounded below. Umbilicus moderately large. 

 Striae rather coarse. 



Raphistoma stamineum Hall. 



Depressed toward the margin, with the central portion of the spire 

 raised somewhat above the outer volution. Sharply angulated on the 

 outer side, nearly flat above and sub-ventricose beneath. 



The surface is marked by strongly elevated, rounded striae, which, 

 bending back from the suture, are interrupted along the center of the 

 upper part of the whorl by a concentric elevated line. Passing the 

 sharp angle of the volution, the striae bend abruptly forward, and, 

 curving gently, pass into the umbilicus. The cast of the inner volu- 

 tions is rounded. 



Raphistoma planistrium Hall. 



Spire depressed. Apex a little elevated. Surface marked by broad, 

 flat, imbricating striae, which are bent backwards and interrupted 

 along a line near the middle of the whorl. Umbilicus small. 



This shell differs from the last in the greater proportional height, 

 the narrow trigonal aperture and the small umbilicus, as well as in the 

 flat, plain striae. 



Raphistoma planistrium variety parvum Hall. 



This differs from the last only in size and a lack of distinct imbri- 

 cating striae. 



Pleurotomaria doc ens Billings. 



Spire nearly flat. Umbilicus closed. On the lower side the whorls 

 are ventricose. At the aperture the outer lip is at right angles to the 

 upper lip or upper surface of the whorl, but this angle decreases as the 

 whorl is followed backward. 



The surface is covered by coarse, slightly elevated undulations of 

 growth. 



