16 



NEW UNIONID.E OF THE 



one is about half the size of that figured. It is a graceful little species, with a re- 

 markably rich satin-like nacre. In the left valve the anterior section of the cardinal 

 tooth is much the larger. . In the right valve it is very small, and there is a disposi- 

 tion in it to be trifid. In outline this species is of a very regular ellipse and is allied 

 on one side to gracilior (nobis), and on the other to glans (nobis). It is rather smaller 

 and thicker than the former, and larger and not by any means so thick as the latter. 

 It would be much more likely to be confounded with the former than the latter. 

 The epidermis is dark brown, smooth and shining like gracilior, and is not so dark' 

 and rough as glam. 



Unio purpurellus. pi. 23, fig. 81. 



Testa laivi, oblonga, subinflata, ad latere planulata, ad basim subcmarginata, postice biangulata, valde 

 inequilaterali; valvulis crassiusculis; natibus prominulis; epidermide tenebroso-fusca et posticii 

 obsolete radiata; dentibus cardinalibus parvis, crenulatis, in utroque valvule subduplicibus j lateralibus 

 prislongis, lamellatis subcurvisque ; margaritfi purpurea et valde iridescente. 



Shell smooth, oblong, somewhat inflated, flattened at the sides, subemarginate at the 

 base, biangular behind ; very inequilateral ; valves a little thick ; beaks somewhat 

 prominent ; epidermis dark brown and obsoletely rayed behind ; cardinal teeth small, 

 crenulate and double in both valves ; lateral teeth very long, lamellar and some- 

 what curved ; nacre purple and very iridescent. 

 Proc. Acad. Nat. Sci., 1857, p, 171. 



Eah. — Flint River, near Albany, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. -5, Length -7, Breadth 1-4 inches. 



Shell smooth, oblong, rather inflated, flattened at the sides or impressed, subemar- 

 ffinate at the base, obtusely biangular behind and very inequilateral ; substance of the 

 shell thick, thicker before; beaks somewhat prominent; ligament rather long, thin 

 and light brown ; epidermis dark brown, obsoletely rayed behind and with not very dis- 

 tant lines of growth ; umbonial slope much raised and rounded, posterior slope slightly 

 raised and roughly striate or wrinkled ; cardinal teeth small, striate, crenulate, pointed 

 and double in both valves ; lateral teeth very long, lamellar, rather thick and somewhat 

 curved; anterior cicatrices small, distinct and well impressed; posterior cicatrices 

 confluent and slightly impressed ; dorsal cicatrices deeply impressed and placed under 

 the plate posterior to the cardinal tooth ; cavity of the shell rather deep and wide ; 

 cavity of the beaks shallow and obtusely angular ; nacre purple and very iridescent. 



Soft Parts. — Branchial uterus occupies the whole width of the outer leaf of the 

 branchia. BrancMcB rather large, the inner rather the larger, free nearly the whole 

 length of the abdominal sack. Palpi rather large, subtriangular, united a short 

 distance on the posterior edges. Mantle thin, thickened and slightly colored on the 

 margin. Branchial opening small, with a few brownish papillae. Anal opening large. 



