41 



TELLINA. 



T, alta. Shell suborbicular or suboval, equilateral, convex, 

 with prominent, acute, concentric striae, and concave intervening 

 spaces, and with minute radiating lines ; lunule small ; lanceo 

 late, slightly impressed; cardinal teeth and anterior lateral tooth 

 compressed and prominent; posterior lateral tooth small but 

 distinct. 



T. papyria. Shell elliptical, equilateral, much compressed ; ex- 

 tremely thin and fragile, with regular concentric impressed striae, 

 most distinct on the anterior side ; posterior extremity angulated ; 

 lunule linear, impressed ; beaks not prominent ; apex acute ; car- 

 dinal teeth prominent ; lateral teeth none. 



CORBIS. 



C. lamellosa. Elliptical, cancellate, with elevated, concentric, 

 remote laminae ; interstices with crowded, regular, transverse 

 strise; inner margin crenulated. 



Corbis lamellosa, Lam. An. sans Vert. vol. v. page 587. 

 Encyc. Meth. pi. 286, fig. 2, a, b, c. 



C. distans. Shell oval, convex, equilateral, with twelve con- 

 centric costae, profoundly elevated and thick, except on the um- 

 bo, and lamellar on the posterior side ; radiating striae distinct ; 

 lunule impressed and carinated ; posterior end subtruncated ; mar- 

 gin crenulated. 



C. undata. Suboval, convex, with radiating striae, and elevated 

 concentric undulations on the umbo, and impressed lines on the 

 inferior portion of the valve, where the radiating lines are obso- 

 lete ; umbo rather ventricose; beaks central, inner margin crenate. 



LUTRARIA. 



L. papyria. Shell ovate, extremely thin and fragile, inflated 

 anteriorly ; with concentric sulci, profound at the anterior and 

 posterior sides, and obsolete at the middle ; and with numerous 

 radiating, interrupted, wrinkled lines; anterior end obtusely 

 rounded ; posterior end cuneiform, compressed and gaping ; 

 beaks elevated, and about one third the length the shell from 

 the anterior end. This shell is allied to L. canaliculata of SAY, 

 but is sufficiently distinct. 



ROSTELLARIA. 



R. laqueata. Subulate, with acute longitudinal ribs, and fine 

 spiral striae : base coarsedy striated. 



Obs. I at first thought this might be the young of R. velata, 

 (nobis.) but a comparison of many specimens proves it entirely 

 distinct. 



[07] 



