﻿I.AMPSILIS 151 



and it is truncate on the lower hinder part. The female shell 

 has a large, wide, rounded marsupial swelling- hehind the cen- 

 tral base, and a sharp posterior point elevated two-thirds of 

 the distance from the base. 



Length (male) 55, height 33, diam. 23 mm. 



Length (female) 40. height 2j, diam. 21 mm. 



Type locality, vicinity of Fort Clarke, Kinney County, Tex. 

 [Armpsilis mearnsi Simpson, Pr. Ac. N. Sci. Phila., 1900, p. 75, 



pi. I, fig. 4; Syn., 1900, p. 564. 



An attractive and remarkable species, which is allied to L. 

 texasensis, but differs in being more robust, more inflated, in 

 having fewer and different ridges on the beaks, and in the color 

 pattern. L. texasensis is unicolored and dark ; in mearnsi 

 there is almost always a very wide, broken ray or squarish 

 blotch and one or more dark, concentric bands on a yellowish 

 ground. 



Lampsilis parva (Barnes). 



Shell long elliptical or subcylindrical, generally a very little 

 wider behind, inflated, subsolid, with full, but not high, beaks, 

 which are turned forward over a narrow lunule, their sculpture 

 consisting of seven or eight single-looped ridges, which are 

 curved up more behind than in front, and return at the posterior 

 end in converging lines to the nucleus ; posterior ridge wanting; 

 epidermis thick and cloth-like, bllackish or fuscous, often brown- 

 ish in the umbonal region ; left valve with two compressed, 

 ragged, recurved pseudocardinals, and two' delicate laterals ; 

 right valve with one pseudocardinal, a minute one above it, and 

 a single lateral; beak cavities and muscle scars shallow, nacre 

 bluish-white, silvery and somewhat iridescent behind, slightly 

 thickened in front. The male and female shells are much alike, 

 the latter being more inflated and a little fuller at the extreme 

 post-basal region. The male shell is usually evenly rounded 

 behind, that of the female is often a Httle truncate and some- 

 times has a blunt point above. The greatest diameter is behind 

 the center of the shell, and the female is remarkable for some- 

 times having the diameter greater than the height. 



