30 DESCRIPTION OP NEW 



My Cabinet. 

 Cabinet of Professor Shepard. 

 Diam. -9, Length 1-7, Breadth 3-4 inches. 



Shell somewhat oblong, transverse, inequilateral, compressed, bian- 

 gular behind, flattened at the umbones and sides, carinate ; substance 

 of the shell rather thick ; beaks scarcely prominent, undulated at the 

 tip; ligament thin, long and straight; epidermis dark brown and ob- 

 scurely rayed ; cardinal teeth small ; lateral teeth very long, curved and 

 enlarged at the posterior end ; anterior cicatrices distinct ; posterior 

 cicatrices confluent; dorsal cicatrices in the centre of the cavity of the 

 beaks ; cavity of the shell rather small ; cavity of the beaks small ; 

 nacre purple and iridescent. 



Remarks. — This shell was procured by Professor Shepard from his 

 friend J. H. Cowper, Esq., with several other fine species. They were 

 found in the canals of the rice fields, where they seem to exist in great 

 perfection. 



The Hopetonensis very closely resembles some of the varieties of 

 complanatus. It differs from it in the teeth, in the carina, and in the 

 possession of a dark border round the inferior part of the margin. In 

 the nacre it appears to be the same, and probably, like the complana- 

 tus, varies into white and salmon colour. 



Unio lugubris. Plate IX. fig. 25. 



Testa elliptica, transversa, suhinfiata, inoiquilaterali, postich biangulata ; valvulis sub- 

 crassis ; natibus proniinulis ; epidermide nigricante; dentibus cardinalibus compressis ; later a- 

 libus sublongis subcurvisque ; margarita purpurea. 



Shell elliptical, transverse, somewhat inflated, inequilateral, biangular behind; 

 valves somewhat thick ; beaks rather prominent ; epidermis nearly black; cardinal teeth 

 compressed; lateral teelh rather long and somewhat curved ; nacre purple. 



Hab. Hopeton, near Darien. Professor Shepard. 



My Cabinet. 

 Cabinet of Professor Shepard. 



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