﻿276 



Ni;i'IIU().\.\IA.S 



(linal and two laterals; rii^lit valve with two pseudocardinals, 

 the upper the smaller, and one lateral ; anterior muscle scars 

 oval, deep ; posterior scars larj^e, shallow ; nacre bluish-white. 



Length ^2, height 32, diam. 18 mm. 



River Michol, at Palenque, State of Chiapas, Mexico. 

 Unio ccruginosus Morelet, Test. Noviss., I, 1849, P- 29.— 



FiscHEi? and Crosse, Miss. Sci., II, 1894, p. 596, pi. i,xii, 



figs. 2, 2a, 2b. 

 Nephronaias ccniginosiis Simpson, Syn., 1900, p. 595. 



The shell fig-ured by Fischer and Crosse is probably a young 

 female. In the Lea collection there are three young shells 

 from Comavaguan. Honduras, labeled Uuio scamnatus that 

 may belong to this species. They are quite pale colored and 

 though worn, show faint rays. 



Nepuron.mas vzABAi.ENSis (Crossc and Fischer). 



Shell inequilateral, rhomboid elliptical, somewhat compress- 

 ed, solid, with a low, double posterior ridge, which ends in a 

 distinct biangulation behind ; surface covered with concentric 

 stria?, slightly lamellated ; epidermis brown-olive with straight, 

 green ravs on the posterior slope ; beaks small, not very prom- 

 inent, their sculpture consisting of concentric ridges ; left 

 valve with one large, ragged pseudocardinal and a triangular 

 pseudocardinal, with two laterals; right valve with tw^o com- 

 pressed pseudocardinals, the upper the smaller, and one lateral ; 

 anterior muscle scars deep ; posterior scars shallow ; nacre 

 bluish-white. The shell figured is no doubt a female, the basal 

 line being decidedly rounded and full in the marsupial region ; 

 the hinder biangulation is considerably elevated above the base 

 line. 



Length 45, height 28, diam. 15.5 mm. 



Lake Yzabal, Guatemala. 

 Unio yzahalensis Crosse and Fischer, J. de Conch.. XL, 1892, 



p 294.— Fischer and Crosse, Miss. Sci., 11. 1804, P- S97. 



pi. LXiv, figs. 4, 4a, 4&. — von Martens, r.iol. Cent. Am., 



Moll., 1900, p. 507, pi. XXXIX, figs. 9-Ti. 

 Nephronaias yzabalensis Simpson, Syn.. i<)oo. p. 5^)6. 



