﻿nf;piirona[As 257 



Nephronaias sapotalensis (Lea). 



Shell irregularly long- elliptical or slightly rhomboid, solid, 

 inflated, the diameter being greatest one-third of the way from 

 the posterior end; beaks low, their sculpture eroded in the 

 specimens examined ; surface smooth, shining, greenish-yel- 

 low with numerous split-up, wavy, elegant rays; left valve 

 with two stumpy pseudocardinals and two strong laterals; 

 right valve with one pseudocardinal and one lateral ; beak cav- 

 ities not deep ; anterior scars well marked ; posterior scars 

 shallow ; nacre brilliant silvery, iridescent behind. 

 Length 56, height 36, diam. 23 mm. 

 Sapotal River, Vera Cruz, Mexico. 

 Unio sapotalensis Lea, Pr. Am. Phil. Soc, II, 1841, p. 30; Tr. 

 Am. Phil. Soc, VIII, 1842, p. 233, pi. xxi, fig. 47; Obs., 

 Ill, 1842, p. 71, pi. XXI, fig. 47.— Chenu, 111. Conch., 1858, 

 pi. XXXIII, figs. 4, 4a, 46. — SowERBY, Conch. Icon., XVI, 

 1868, pi. xEi, fig. 495. — Fischer and Crosse, Miss. Sci., 



II, 1894, p. 601, LXVII, figs. 2, 2a. 

 Margaron (Unio) sapotalensis Lea, Syn., 1852, p. 29; 1870, 



P- 45- 

 Nephronaias sapotalensis Simpson, Syn., 1900, p. 592. 

 Nephronajas sapotalensis Ortmann, Ann. Car. Mus., VIII, 



1912, p. 326, fig. 21. 



I have only seen two shells of this species, both of which 

 are probably females, one being considerably and the other 

 strongly produced at the post-basal region. The species seems 

 to be closely related to .¥. medellina, but is shorter, more in- 

 flated, more brilliantly painted, and its greatest diameter is 

 nearer the posterior end than it is in that form. 



Nephkonatas computata (Crosse and Fischer). 



"Shell slightly inequilateral, oval-elliptic, rather thick, 

 heavy, a little inflated ; epidermis smooth, shining, yellow, 

 with narrow, greenish rays, slightly separated, but becoming 

 closer posteriorly ; anterior margin rounded ; posterior margin 

 obliquely subtruncate ; basal margin curved, not sinuate ; dor- 

 sal margin slightly curved before and behind the beaks ; beaks 



