﻿UNITED STATES. 201 



cardinalibus parvis, pyramidatis crenulatisque; lateralibus sublongis, lamellatis subcurvisque ; mar- 

 garita vel purpurea vel salmonis colore tincta et iridescente. 



Shell smooth, oblong, rather inflated, flattened at the side, inequilateral ; valves 

 rather thin, thicker before; beaks a little prominent, undulate at the tips; epidermis 

 blackish, shining and obscurely rayed; cardinal teeth small, pyramidal and crenulate ; 

 lateral teeth rather long, lamellar and somewhat curved; nacre either purple or 



salmon color and iridescent. 



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



Hob. — Streams near Columbus, Georgia. Bishop Elliott. 



My cabinet and cabinet of Bishop Elliott. 

 Diam. -5, Length -8, Breadth 1-5 inches. 



Shell smooth, oblong, rather inflated, flattened at the sides, inequilateral, rounded 

 behind ; substance of the shell rather thin, a little thicker before ; beaks a little 

 prominent, finely undulate at the tips; ligament short, somewhat thick and light 

 brown ; epidermis blackish, shining, obscurely rayed and with rather distant marks 

 of growth ; umbonial slope raised and much rounded: cardinal teeth small, pyramidal, 

 crenulate, compressed and double in both valves ; lateral teeth rather long, lamellar 

 and somewhat curved ; anterior cicatrices distinct ; posterior cicatrices confluent ; 

 dorsal cicatrices placed under the plate immediately behind the cardinal tooth; 

 cavity of the shell rather deep and wide; cavity of the beaks rather shallow and 

 subangular ; nacre purple* and salmon color. 



Soft parts. — Branchial uterus not charged, but ova were found in the ovarium. 

 Branchial free nearly the whole length of abdominal sack, large, rounded below, 

 inner one much the larger. Palpi rather small, subangular, united above on the 

 posterior edges. Mantle thickened and double on the posterior margin, colored at the 

 siphonal openings and truncate lehind. Branchial opening very large, with numerous 

 small brown papillas on the inner edges. Anal opening large, with very minute, 

 brown papillse on the inner edges. Super-anal opening rather small, colored within 

 and slightly united below. Color of the mass dirty white. 

 ' Remarks. — This little, very dark brown or blackish species, is very nearly allied 

 to nigellus (nobis). It is rather more transverse, not quite so high on the umbonial 

 slope, nor has it so smooth, dark and polished an epidermis. One of the youngest 

 specimens is perfect at the beaks and displays a number of irregular undulations 

 very much like those of complanatus. This young one is light brown and has well 

 marked rays on the posterior half, while the adults have very obscure ones or none. 



Unio radians. PI. 23, fig. 84. 



Testa laevi, elliptica, subinflata, insequilaterali, postice rotundata ; valvulis subtenuibus, antice crassioribus, 

 natibus prorninulis, ad apices undulatis ; epidermide lutea, polita, vald^ radiata; dentibus cardinalibus 

 subgrandibus, erectis, subconicis crenulatisque ; lateralibus sublongis, lamellatis subrectisque j mar- 

 garita vel alba vel rosacea et valde iridescente. 



