﻿OBOVARTA 299 



(.Ji}OVARi A I'lj.ipsis (Lea). 



Shell usually evenly elliptical, sometimes rather ovate, in- 

 flated, solid, with high beaks placed close to the anterior end 

 and turned forward over a small lunule, their sculpture con- 

 sisting of a few somewhat doubly looped bars ; posterior ridge 

 scarcelv developed ; anterior end rounded or subtruncate ; sur- 

 face nearly smooth or having a few shallow, irregular sulca- 

 tions ; epidermis greenish or yellowish-brown, with faint, 

 darker rays ; left valve with two pseudocardinals, the posterior 

 one nearly parallel with the stout, curved laterals ; right valve 

 usually with three pseudocardinals, the two outer ones small, 

 the middle and upper ones in all shells parallel with the strong 

 double lateral ; beak cavities shallow, showing a row of dorsal 

 scars; muscle scars small, impressed, the anterior ones roug'h ; 

 nacre silvery white, much thickened in front. The shells of 

 the male and female dilfer but little, those of the latter being 

 a very little more produced at the post-basal part than the 

 former. 



Length 75, height 56, diam. 45 mm. 



Length 63, height 47, diam. 35 mm. 



Upper Mississippi system as far south as the Tennessee and 

 Arkan.sas Rivers : St. Lawrence drainage area. 



Type locality, Ohio. 

 ? Unio hrcvialis Sowi£ri;v. Rec. and Foss. Shells, XVI, 1823, 



Unio ellipsis Lea, Tr. Am. Phil. Soc, IH, 1828, p. 268, pi. iv 

 fig. 4; Obs., L 1834, p. 10, pi. IV. fig. 4.— Say, Am. Conch. 

 L 183 1, pi. XIV.— Hanley, Biv. Shells, 1843, p. 188, pi. xxi 

 f^o-. 7._p()Tirz and Michatjd, Gall. Moll., 1844, p. 150, pi 

 LViii, figs. I, 2.— Chenu. Bib. Conch., ist ser.. Ill, 1845, p 

 22, pi. IV. figs. I, I a. \b. — KusTER, Conch. Cab. Unio, 1852 

 p. '43, pi. viii. fig. 4.— Chenu, 111. Conch., 1858, pi. xviii 

 figs. I, \a. \h. — SowERBY, Conch. Icon., XVT, 1868, pi. lxxx 

 fig. 424. 



Margarita (Unio) ellipsis Lea, Syn., 1836, p. 22 ; 1838. p. 18 



