106 



[ Senate 



Pentamerus pseudogaleatus. 



Pal. N.Y. Vol. iii, pi. 46, f. 2. 



Shell longitudinally ovate : ventral valve extremely convex, 

 especially in the umbonial region ; beak very prominent and 

 strongly gibbous, incurved, and projecting far beyond that of the 

 other valve ; front margin in adult shells sometimes having a 

 faint mesial prominence : dorsal valve subcircular, or much 

 shorter and more compressed than the opposite ; beak incurved ; 

 front obliquely flattened, or very slightly depressed so as to tbrm 

 sometimes an indistinct sinus, often a little produced into a short 



FSHTAHESUS TSEVDOQALTSXTVS, 



