AND OTHER FAMILIES. 143 



minent, rounded ; ligament rather short and thick ; epidermis dark 

 brown or black ; cardinal teeth wide, striate, but not divided ; lateral 

 teeth somewhat curved, serrate and separated from the cardinal teeth 

 by the absence of a plate ; anterior cicatrices distinct, posterior cica- 

 trices confluent and large ; dorsal cicatrices situated across the cavity 

 of the beaks and very distinct ; cavity of the beaks large and rounded ; 

 nacre pearly and pink coloured. 



Remarks. — This very distinct species is one of the many fine shells 

 collected by Mr Stewart in the Bayou Teche. It perhaps most re- 

 sembles an inflated specimen of U. cuneatus (Barnes). It may, how- 

 ever, at once be distinguished from that species by its peculiarly beau- 

 tiful pinky lustre and striate cardinal teeth, as well by its globosity. 

 The stricT of the cardinal teeth diverge from a point beneath the 

 point of the beaks, and in its flatness and absence of a cleft these 

 teeth resemble those of the U. rubiginosus (nobis). 



Unio cAPSiEFORMis. Plate II. fig, 4. 



Testa ellipiicu, transversa, inxquilaterali, subinflatd, postice subtriangxdatd ; 

 valvulis anticc crassioribiis ; natibus prominulis ; dentibus utriusque valvulse car- 

 dmalibus, elevatis dupUcibusque ; lateralibus elevatis et lamellatis ; margaritd 

 alba et iridescente. 



Shell elliptical, transverse, inequilateral, somewhat inflated, sub-biangulate poste- 

 riorly ; valves thicker anteriorly ; beaks slightly elevated ; cardinal teeth elevated and 

 double in both valves ; lateral teeth elevated and lamellar ; nacre pearly white and iri- 

 descent. 



Hab. Cumberland River. W. Cooper. 



My Cabinet. 



Cabinet of W. Cooper. 



Cabinet of the Academy of Natural Sciences of Philadelphia. 



Diam. .9, Length 1.3, Breadth 1.9 inches. 



Shell elliptical, transverse, inequilateral, somewhat inflated, flattish 



before the umbonial slope, sub-biangulate posteriorly ; substance of the 



