198 TESTACEOUS MOLLUSCA. 



in Lain. 6. p. 552. Ovate oblong, transverse, subdepressed, pos- 

 teriorly obtuse, anteriorly obscurely angulated, striated, dark olive, 

 nacre rosy ; cardinal teeth very salient and compressed in one valve, 

 in the other short and bifid. Senegal and the Nile. 



U. Egyptiacus. Cail. voy. a Meroe. 2. t. 61. f. 6, 7. — 

 Desk, in Lam. 6. p. 353. Oval-oblong, turgid, subinequilateral, 

 thin, anteriorly broad and dilated ; cuticle olive rayed with yellow, 

 nacre pink and irri descent ; hinge almost linear, with two teeth, 

 the anterior lamella very narrow and acute. Egypt and Senegal. 



1 1 1 t Oblong. 



U. Brevidens. Lea. in Am, Ph. Tr. 4. (1837.) ;?-75. t. 6.f. 

 6. Oval-oblong, subtriangular, transverse, thick, inequilateral, 

 umbonal slope curved ; beaks slightly prominent, ligament short, 

 ventral edge subincurved in the middle ; cuticle yellow and wrin- 

 kled, rays small slightly curved and interrupted ; nacre pearly white, 

 cardinal tooth rather small, slightly elevated and rather cleft in 

 one valve, simple and emerging from a pit in the other, lateral teeth 

 short and thick. 1-^ . . 1 ^. — Ohio. 



U. Tetralasmus. Say. Am. Con. t. 23. Transversely oblong- 

 elliptic, thinnish, convex, hinge margin parallel to the ventral and 

 subrectilinear ; posteriorly very short and rounded, anteriorly slop- 

 ing obliquely from the hinge margin to the rounded extremity ; 

 anterior slope with two impressed lines ; beaks little elevated, de- 

 corticated, umbonal slope not prominent : inside white, irridescent 

 anteriorly and on the margin ; lateral teeth two in each valve. 3£. — 

 New Orleans. 



U. Camptodon. Say. Am. C. £.42. — Declivis. Conr. (fide 

 Lea.) Transversely oblong-oval, moderately thin, a little com- 

 pressed, not very inequilateral, blackish or dark brownish, dorsal 

 line sinuated, obtusely angulated at each extremity ; the ventral edge 

 incurved in the middle, and rounded at each extremity : anterior 

 slope somewhat compressed, with two distinct compressed lines ; um- 

 bonal slope not elevated above the level of the disc ; beaks with 

 small undulations, little prominent ; within milk white, a single 

 rather long oblique undivided primary tooth in each valve, the 

 lateral teeth rather slender towards the tip, a little arcuated. 2 . ,3£. 

 — New Orleans. 



U. Obesus. Lea. on U. 1. p. 106. (andTr. Am. Ph. 4.) t. 13. 

 f. 26. Ovate-rhomboidal, oblique, inequilateral, inflated, thickish, 

 angular anteriorly, ventral edge little rounded ; beaks rather pro- 

 minent, ligament long and large ; cuticle fuscous and much wrinkled, 

 nacre livid white ; cardinal teeth elevated and crested, lateral long 

 and curved. 2 . .3-^. — Virginia. 



U. IIopetonensis. Lea. on U. 2. (Tr. Am. 6.) p. 29. t. 9. 

 /*. 24. Suboblong, transverse, inequilateral, compressed, biangular 



