46 BuivivETiN 5 316 



140 FOSSIL SHELI.S. 



Length nearly seven-tenths of an inch, breadth 

 less than one inch and a fifth. 



PBCTUNCUIvUS. 



P. subovatus. PI. X. fig. 4. Longitudinally short 

 ovate, vi^ith about thirty longitudinal impressed 

 acute lines, the intervals a little convex. 



Description. Shell increasing in width by a 

 slightly curved line from the apex to beyond the 

 middle : lateral curvatures equal : apices separate, 

 small, central ; intervening space with but little 

 obliquity to the plane of the shell, with obsolete 

 angulated lines : teeth forming a regularly and much 

 arcuated series, which is rectilinearly truncated 

 above so as to leave in that part a mere edentu- 

 lous elevated line : within destitute of striae : mar- 

 gin with elevated angular lines : exterior surface 

 with about thirty longitudinal, impressed, acute 

 lines, the intervals a little convex. 



Length from the apex to the base one inch and 

 thirteen-twentieths, breadth one inch and a half 

 nearly. 



The character of the interval between the beaks 

 is not unlike that of a Cucull^a, but the arrange- 

 ment of the teeth does not correspond with the 

 definition of that genus. 



This shell varies a little in form, being some- 

 times nearly orbicular. 



[J. A. N. S., Phila., ist Sen, Vol. IV, 1824.] 



