﻿172 I.AMI'SILIS 



♦ 



Lami'Sii.is i'.i:ki. AMiii'.Kii (Lea). 



Shell somewhat rhomlxjid, inflated, solid, with full, higii 

 beaks, a large ligament and a very low wing; beak sculpture 

 almost wanting; surface with irregular growth lines, nearly 

 smooth, nearly or quite rayless, the young shell pale brownish, 

 adult or old shells dark brown ; posterior ridge rather high and 

 rounded ; left valve with two high, ragged pseudocardinals and 

 two short, remote, club-shai)ed laterals ; right valve with two 

 pseudocardinals, the u]>])er smaller, and one lateral ; beak cav- 

 ities full and deep, with a few scars under the shelf of the 

 hinge ; anterior muscle scars deep ; posterior scars very large 

 in adult shells, suborbicular ; nacre purplish, much thicker in 

 front. In both male and female shells the rounded posterior 

 point is below the median line, the female shell is but very lit- 

 tle fuller on the posterior base than that of the male. 



Length 105, height 75, diam. 50 mm. 



Northeastern Mexico : southwestern Texas. 



Type locality, Matamoras and Tamaulipas, Mexico ; Colora- 

 do River, Texas. 

 Unio berlandierii Lea, Pr. Ac. N. Sci. Phila., T, 1857, p. loi ; 



Jl. Ac. N. Sci. Phila., IV, i860, p. 369, pi. lxv, fig. 194; Obs., 



VIII, i860, p. 51, pi. Lxv, fig. 194. — Reeve, Conch. Icon. 



XVI, 1865, pi. XXIII, fig. 108. 

 Mar gar on (Unio) berlandierii Lea, Syn., 1870, p. 36. 

 Lampsilis berlandieri Simpson, Syn., 1900, p. 570. 



A larger, solider, more inflated and more rhomboid shell 

 than umbrosa. having higher, fuller beaks and larger, deeper 

 beak cavities. 



Lampsilis tampicoensis (Lea). 



Shell subrhomboid, scarcely inflated, subsolid. with moder- 

 ately full beaks, which have exceedingly faint sculpture, with a 

 small, rounded posterior ridge; surface rather smooth, with a 

 glossy, dark chestnut or blackish epidermis ; left valve with 

 two subcompressed pseudocardinals and two remote slightly 

 curved laterals; right valve with two pseudocardinals, the 

 lower the higher, and one lateral ; beak cavities deep, compress- 



