﻿48 LAMPSILIS 



A species, which seems to be only locally abundant, being 

 found in the Mississippi in considerable quantities at various 

 points in Iowa, notably Davenport and the mouth of the Iowa 

 River. It is very much inflated, having- the fullest umlx>nal 

 region of perhaps any Unione known ; the hinge line is re- 

 markably curved, the epidermis almost invariably has a smoky 

 hue and is rayless, and the shell gapes at the anterior base and 

 the posterior end. 



Lampsilis ovata (Say). 



Shell subrhomboid to elliptical, solid, somewhat inflated, 

 with high, full beaks, which have a few coarse ridges nearly 

 parallel with the growth hues ; posterior ridge high and sharp ; 

 surface with irregular, rude growth lines; epidermis rather 

 smooth and shining on the disk, somewhat roughened and 

 wrinkled on the posterior slope, straw-color, tawny, pale olive 

 or brownish, rayless or feebly rayed ; Hganient large and prom- 

 inent ; left valve with two somewhat compressed pseudocar- 

 dinals in front of the beak, the hinder the smaller, with two 

 rather short, distant laterals, the middle of the hinge plate 

 narrowed and rounded ; right valve with two opposite pseudo- 

 cardinals, separated by a deep, parallel-sided socket, the upper 

 smaller and much compressed, with one remote, high, sharply 

 truncate lateral ; beak cavities deep, not wide ; muscle scars 

 shallow, smooth, the hinder large, rounded or semilunar ; nacre 

 whitish. The female shell is but slightly inflated in the post- 

 basal region. 



Length 140, height 95, diam. 55 mm. 

 Ohio River drainage ; Rome, Georgia ? 

 Type localitv, Ohio River and its tributary streams. 

 Uniu oiatiis Say, Nich. Encyc, II. 1817. pi. 11. fig. 7. — Con- 

 rad, Monog., I, 1835, p. 4. pi. II.— KusTKR, Conch. Cab 

 Unio, 1852, p. 22, pi. HI, fig. 2. — SowiiRBY, Conch. Icon., 

 XVI, 1866, pi. XXXI, fig. 164. 

 Margarita (Unio) ovatits Lha, Syn., 1836, p. 19; 1838, p. 17. 

 Margaron (Unio) ovatus Lea, Syn.. 1852, p. 24; 1870. p. ^,7. 

 Lampsilis ovatus Simpson. Syn., 1900, p. 530. 



