﻿76 I.AMI'SII.IS 



l.cngth (male) 80, licig"ht 47. diani. 28 mm. 



Length (female) 75, height 48, diam. 28 mm. 



Salina and Clinton, Arkansas ; Guadalupe River, Texas ; 

 Spring "River, Kansas (Cragin). 



Type locality, Saline River, Ark. 

 Unio poweUii Lka, Pr. Am. JMiil. Soc, A\ 1852, p. 252; Tr. 



Am. Phil. Soc., X, 1853, p. 270, pi. xix, fig. 25; Obs,, V, 



1852, p. 26, pi. XIX, fig. 25. — MusGRAVE, Phot. Conch., 1863, 



pi. II, fig. 8. — SowERBY, Conch. Icon., XVT, 1868, pi. lxx, 



fig- 359- 

 Mar gar on (Unio) poufellii Lka, Syn., 1852, p. 28, 1870, p. 44. 

 Lampsilis pozwllii Simpson, Syn., 1900, p. 538. 



This species is close to L. rec7'jana and is perhaps only a 

 variety of it. It is a little solider than that species, especially 

 at the edges of the shell, is rayless, and has a somewhat differ- 

 ent texture. 



Group oi Lampsilis orhiculata. 



Shell elliptical, sub(|uadrate or ovate, verv solid, more or 

 less inflated, slightly gaping at the anterior base; beaks well 

 in front, large, full and high, their sculpture consisting of 

 faint, scarcely looped ridges ; epidermis tawny to dark, smooth, 

 scarcely showing rays ; lunule deep and distinct, passing under 

 the beaks; hinge and teeth strong; there are two pseudocar- 

 dinals in the left valve and two to three in the right ; two lat- 

 erals in the left valve and one in the right ; muscle scars well 

 impressed ; nacre bright. Animal with large gills, which are 

 rounded below, inner much the larger, united their whole 

 length to the abdominal sac ; paljii large, thick, oblique, oval ; 

 branchial opening very large : anal o])cning rather large, both 

 having many small papillae. 



I.AMPSius ORRicui.ATA (Hildrcth). 



Shell somewhat inflated with a well-marked posterior ridge, 

 elliptical, solid, gaping at the anterior base; beaks moderately 

 elevated, with very faint sculpture: lunule elongated, surface 

 generally having wide, low, concentric ridges, the rest periods 



