﻿TRUNCILLA T r 



ties shallow ; nacre flesh-color, inclining- to reddish behind. 

 Male shell with a well-developed posterior ridge, which is nar- 

 rowly rounded, generally subtriangular in outline ; female 

 shell subquadrate, the marsupial area slightly raised and pro- 

 duced at the base, feebly radially striate. 



Length (male) 25.5, height 19, diam 15 mm. 



Length (young female) 19, height 14, diam. 9.5 mm. 



Type locality, Connasaugiia and Chattanooga Rivers, north- 

 west Georgia. 

 Unio niodicellus Lea, Pr. Ac. Nat. Sci. Phila., Ill, 1859, p. 



171 ; Jl. Ac. Nat. Sci. Phila., IV, i860, p. 347, pi. lvii, fig. 



172 ; Obs., VIII, i860, p. 29, pi. LVii, fig. 172. 

 Margaron (Unio) modicellus Lea, Syn., 1870, p. 41. 

 Trimcilla modicella Simpson, Syn., 1900, p. 518. 



A small species, the male sh-ells of which look as though 

 they might be a Pleurobema of the riuhellum group. The fe- 

 male shell shows it to be a Truncilla of the hreindens group. 

 It is smaller than any of the other species, dull colored, and, so 

 far as I have seen, is rayless. 



Truncilla lenior (Lea). 



Shell scarcely subsolid, somewhat inequilateral, subinflated 

 to inflated, with delicate growth lines; beaks but little elevated, 

 sculptured with irregular, doubly-looped bars ; epidermis pale 

 ashy-greenish or yellowish-green, with numerous narrow ravs 

 on the posterior half of the shell ; pseudocardinals delicate, 

 subcompressed, roughened ; laterals short ; nacre flesh-colored, 

 brilliant. Female shell subquadrate, a little narrower in front ; 

 marsupial swelling well developed, marked off behind by a 

 sulcus and with the hinder end of the shell radially sculptured 

 and toothed, excavated within ; posterior scars large, impressed. 



Length (female) 25, height 16, diam. 13 mm. 



Length (female) 24, height 15.5, diam. 10 mm. 



Type locality. Stones River, Tennessee; also Paint Rock 

 River, Woodville, Alabama. 

 Unio lenis Lea, Pr. Am. Phil. Soc. I, 1840, p. 286. 



