﻿PLAGIOLA 3^5 



Plagioi.a SAL.T.E1 (Crosse and Fischer). 



' Shell very solid and inflated, triangular ovate, inequilateral, 

 with a high, narrow, generally slightly biangular dorsal ridge; 

 beaks full and high, their sculpture not observed; epidermis 

 rough, blackish, often inclined to crack off; left valve with 

 two pseudocardinals, the hinder triangular, the anterior sub- 

 compressed, and two short, remote, solid laterals, the lower 

 the larger ; , right valve with one large, triangular pseudo- 

 cardinal, sometimes with a feeble second one above it, and 

 one lateral; hinge plate rather narrow; beak cavities fairly 

 deep ; muscle scars deep ; nacre white, much thickened in front. 

 Male shell nearly or quite straight on the base, the posterior 

 biangulation reaching to the base line; female shell with a 

 decidedly produced marsupial swelling, its slight posterior 

 biangulation elevated to near the middle of the height of the 

 shell. 



Length (male) 65, height 43. diam. 31 mm. 



Length (male) 65, height 43, diam. 31. mm. 



Length (female) 50, height 37, diam. 32 mm. 



Mexico; Usumacinta and Rio Salinas rivers, Guatemala. 

 Unio sallei Crosse and Fischer, J. de Conch., XLI, 1893, p. 



17c).— Fischer and Crosse, Miss. Sci., IL 1894- P- 619, pl- 



Lxviir, figs. 3. 3fl. 



Var. grossa (von Martens). 



Shell shorter and higher than the type, very solid, anterior 

 end rounded below, obliquely truncated above ; posterior ridge 

 well defined. 



Length 62, height 44, diam. 30 mm. 



Guatemala. 

 Unio sallei var. oj'ossiis von Martens, Biol. Cent. Am., :\[oll.. 



1900, p. 517, pl. XXXTV, figs. 2, 2a, 2b. 



There is in the National Museum collection a badly eroded 

 old female shell sent by von Ihering from the Usumacinta 

 River, Guatemala, that T 1)elieve belongs to the above species ; 

 probably to von IMartens' variety of it. It is a dead shell. 

 verv old and somewhat diseased. The anterior half of the shell 



