94 NEW UNIONID.E OF THE 



The abdominal sack with the foot both very small, and the larger portion of the 

 branchige are posterior to the abdominal sack. 



Remarhs. — A number of specimens in alcohol were received from Mr. Plant. It is 

 nearly allied to exfensus (nobis), but is more compressed, and the angle on the um- 

 bonial slope is more pronounced and the epidermis is darker. I have not seen any 

 young individuals, and therefore cannot say if they ever have any rays, nor can I give 

 the character of the undulations of the beaks. 



Unio naviculoides. pi. 20, fig. 74, 



Testa ]a5vi, transversa, subinflata, postice biangulata, valde inequilaterali ; valvulis tenuibus ; natibus promi- 

 nuHs ; epidermide tenebroso-fusca, eradiata, striata ; dentibus cardinalibus parvis. compressis, trigonis, 

 in utroque valvulo duplicibus crenulatisque ; lateralibus prreloagis, lamellatis subrcctisque ; mar- 

 garita purpurea et iridescente. 



Shell smooth, transverse, somewhat inflated, biangular behind, very inequilateral ; 

 valves thin ; beaks a little prominent ; epidermis dark brown, without rays, striate ; 

 cardinal teeth small, compressed, triangular, double in both valves and crenulate ; 

 lateral teeth very long, lamellar and nearly straight ; nacre purple and iridescent. 

 Proc. Acad. Nat. Sci., 1857, p. 170. 



Bah. — Buckhead Creek, Burke County, Bishop Elliott; and Macon, Georgia, J. C. 

 Plant. 



My cabinet and cabinets of Bishop Elliott and Mr. Plant. 

 Diam. -8, Length lo. Breadth -3 inches. 



Shell smooth, transverse, somewhat inflated, very inequilateral, biangular behind 

 and regularly rounded before ; substance of the shell thin ; beaks slightly prominent ; 

 ligament long and thin ; epidermis dark brown, striate, without rays, with numerous 

 well marked lines of growth ; umbonial slope raised into an obtuse angle ; cardinal 

 teeth small, compressed, triangular, crenulate, oblique, and double in both valves ; 

 lateral teeth very long, lamellar and nearly straight ; anterior cicatrices distinct and 

 moderately impressed ; posterior cicatrices confluent and scarcely perceptible ; dorsal 

 cicatrices very small and placed in the centre of the cavity of the beaks ; cavity of 

 the shell rather shallow and wide ; cavity of the beaks very shallow and rounded ; 

 nacre purple and iridescent. 



Soft Parts. — Branchial uterus charged the whole width, except at the extreme 

 ends. Branchiae large, gently curved below, the inner one much the larger, free 

 about two-thirds the length of abdominal sack. Palpi rather small, transverse, sub- 

 oval, united only at the upper part of the posterior edges. Mantle thin, slightly 

 thickened at the margin which is rather broad. Branchial opening rather large, 

 angular below, with numerous small brownish papillae on the inner edges. Anal 

 opening large, with numerous very small brownish papillfe on the inner edges. 

 Super-anal opening rather small, united below for some distance. Color of the mass 

 whitish. 



