94 



Unio Cuprinus. Plate XII. fig. 24. 



Testa ovatd, transversa, inmquilaterali, inflatd, postico latere latissimo; valvulis 

 tenuibus; natibus parvis undulatisque; dentibus cardinalibus exiguis, lateralibus 

 laminatis; ligamento longo; margaritd cupred. 



Shell reversely ovate, transverse, inequilateral, inflated; valves thin; beaks small 

 and undulated; cardinal teeth small; lateral teeth thin and lamellar; ligament long; 

 nacre copper colour. 



Hab. Mexico, J. R. Poinsett, Esq. 



My Cabinet. 



Cabinet of the American Philosophical Society. 



Diam. -9, Length 1-1, Breadth 2"1 inches. 



Shell reversely ovate, transverse, inflated, disposed to be straight in 

 the basal margin ; substance of the shell thin ; beaks small, pointed, 

 furnished with concentric undulations and placed near the anterior 

 margin ; ligament long, lanceolate ; umbonial slope large and rounded ; 

 posterior slope elevated into a carina; epidermis reddish brown and 

 wrinkled ; rays obsolete ; cardinal teeth very small and tuberculated ; 

 lateral teeth slender, lamellar and nearly straight ; antei"ior and poste- 

 rior cicatrices both confluent; dorsal cicatrices in the centre of the 

 cavity of the beaks; cavity of the beaks wide; nacre copper colour and 

 very brilliant towards the posterior margin. 



Remarks. — This remarkable shell is one of the many fine specimens 

 of the splendid collection of interesting subjects brought by our fellow 

 member J. R. Poinsett, Esq. from Mexico, and which, by his munifi- 

 cence, now constitutes a valuable part of the collection of this society. 

 In comparing this species with the others of the genus, we shall find 

 it most to resemble the complanaitis (Solan.). It differs however in 

 having the posterior dorsal margin more elevated, in the peculiar cop- 

 per colour of the nacre, and in the concentric undulations of the beaks. 

 In the specimens which I have had an opportunity of examining, the 

 anterior cicatrices were found to be confluent, a circumstance rarely 

 met with in the Uniones. 



