﻿LAMPSILIS 49 



Unto ovata Lamarck, An. sans Vert., VI, 1819, p. 75. — ? Vai^- 



ENCiENNES, Coq. Marines, Biv., 1833, pi. l, figs, i, la, ih, ic. 

 Lampsilis ovata RaFinbsque, Ann. Gen. Sci. Phys. Brux., 



V, 1820, p. 298. 

 Mya ovata Eaton, Zool. Text-Book, 1826, p. 218. 

 j^glia ovata Swainson, Treat, on Mai., 1840, p. 266, fig. 49. 



This species is characterized by its strong, sharp posterior 

 ridge, which is generally wanting, or low, in L. ventricosa. 

 The only other species of the group which has a similarly de- 

 veloped ridge is L. excavata, which is a smaller, more inflated 

 and usually rayed form with the marsupial swelling more dis- 

 tinctly developed. 



The name ovatus was used for Unto tumidus Retz, by Lis- 

 ter, Donovan, and others, but as it was called a Mya and the 

 g-eneric name Unto was never used with it, it can stand for 

 Say's species. 



Lampsilis ochracea (Say). 



Shell thin, subinflated, elliptical, with rather full beaks, which 

 are sculptured with a few straight, strong ridges; posterior 

 ridge well developed, and ending in a blunt point about half 

 way up from the base of the shell ; epidermis dull, scarcely 

 shining, tawny-brownish, generally lurid or smoky and lamel- 

 lated over the posterior part of the shell, generally feebly 

 rayed ; left valve with two rather small pseudocardinals in 

 front of the beaks, which are compressed and often grown 

 together, the anterior the highest, with two thin, remote lat- 

 erals ; the hinige line is narrow and rounded at the middle ; 

 right valve with two triangular, compressed pseudocardinals 

 opposite each other and separated by a deep, narrow pit, the 

 upper the smaller, and a thin, truncated lateral ; muscle scars 

 shallow ; beak cavities moderate ; nacre lurid, tinged with red- 

 dish or purplish. 



Length 115, height 70, diam. 60 mm. 



Length 80, height 50, diam. 35 mm. 



Atlantic drainage, from New England to the Ogeechee 

 Kiver, Georgia. 



Type locality, Delaware and Schuylkill Rivers, 



