218 DESCRIPTION OF 



Hab. Chattahoochee River, near Columbus, Georgia. Dr. Boykin. 

 My Cabinet, and Cabinet of Mr. Nicklin. 

 Diam. .9, Length , 1.4 Breadth 2.2 inches. 



Shell folded on the posterior slope, triangular, rather inflated ; substance of 

 the shell thick, thinner behind; beaks somewhat prominent; ligament short 

 and thick; epidermis nearly black; cardinal teeth small, lobed and striate; late- 

 ral teeth long and nearly straight; anterior cicatrices distinct; posterior cicatrices 

 confluent; dorsal cicatrices placed on the under side of the plate between the 

 cardinal and lateral teeth; cavity of the shell rather shallow; cavity of the beaks 

 shallow and subangular; nacre salmon-coloured, purple or white, and very iri- 

 descent behind. 



Remarks. — Specimens of various ages of this species were kindly sent to me 

 by Dr. Boykin. In general outline and appearance it closely resembles U. 

 crassidens, Lam., but is a much smaller species. It belongs to that great 

 group of which the U. complanatus, may be considered the type. Among 

 the numerous specimens before me, the salmon colour prevails greatly, purple 

 being the rarest. In the young specimens obscure rays may be observed, in 

 the adults the umbonial slope is usually angular, and bounds the folds, which 

 are not numerous. 



Unio delphinus. Plate 17, Fig. 35. 



Testa alata,lata, compressd, postice biangulata, valdc incequilaterali; aid elevata, acuminata, duplici; 

 valvulis subcrassis; natibus vix prominentibus; epidermide tenebroso-fuscd; dentibus cardinalibus par- 

 vis, crenulatis; lateralibus longissimis rectisque; margaritd alba et iridescenfe. 



Shell winged, wide, compressed, biangular behind, very inequilateral; wing high, acuminate and double; 

 valves somewhat thick; beaks scarcely prominent; epidermis dark brown; cardinal teeth small, crenulate; 

 lateral teeth very long and straight; nacre white and iridescent. 



Hab. New Holland.? G. Von den Busch, M. D. 



My Cabinet, and Cabinets of Dr. Von den Busch and Mr. Gruner of Bremen. 

 Diam. 1.2, Length 3.6, Breadth 5.5 inches. 



Shell winged, wide, compressed, biangular behind, subangular on the um- 

 bonial slope, with numerous very minute granulations over the disk, very ine- 

 quilateral; wing high, duplex, terminating in two points, the anterior one being 

 the highest and acutely pointed; substance of the shell rather thick; beaks 

 scarcely prominent; ligament concealed, except the posterior part, which is 



