﻿ANODONTA 38 I 



Anouonta coarctata Anton. 



Shell rhomboid or subtrapezoidal, quite inequilateral, con- 

 vex, thin, with a shining, olive epidermis ; surface finely, con- 

 centricall}- striated ; beaks low but pointed ; post-dorsal region 

 elevated, rounded behind, the posterior slope truncated; base 

 line straight ; anterior end rounded or subtruncate above ; nacre 

 bluish-white. 



Length 51, height 34, diam. 18 mm. 



Lake Chapala, State of Jalisco, Mexico. 

 Anodoiita coarctata Anton_, \'erz. der Conch., 1839, p. 16. — 



KusTER. Conch. Cab. Ano., 1853, p. 34, pi. vm^ fig. 2. — 



Simpson, Syn., 1900, p. 630. — von Martens, Biol. Cent. 



Amer., Moll, 1900, p. 525, pi. xl, figs. 1-7.— Dall, Pr. L. 



S. Nat. Mus., XXXV, 1908, p. 180, pi. xxix, figs. 3, 4. 

 Andonta chapalensis Crossr and Fischer, J. de Conch., XL, 



1892, p. 2()5. — Fjschkr and Crosse, Miss. Sci.. H, 1894, p. 



518, pi. lxiv, figs. 8-11. 

 Anodonta cygnca impura (part), Hannihal, I'roc. Mai. Soc. 



London, X, 1912. p. 125. 



Anton very hrietly described his species, but did not figure 

 it. Kuster gives a figure in the Conchylien Cabinet. The speci- 

 mens figured as A. chapalensis in the Mission Scientifique so 

 closely agree with Kuster's figure of coarctata that I cannot 

 believe that they are distinct. The shell is subriiomboid or 

 subtrapezoid instead of being obovate like A. cxilior. 



Anodonta exilior Lea. 



Shell is rather small or medium size, somewhat obovate, in- 

 equilateral, rather full, with a moderate post-dorsal wing, be- 

 hind which it is only subtruncate ; posterior ridge scarcely de- 

 veloped, rounded ; beaks low. compressed, their sculpture con- 

 sisting of faint, straight or slightly corrugated ridges ; surface 

 smooth : ej^idermis greenish-olive sometimes brownish, occa- 

 sionalK- banded and clcnided with d:irk iireen, shining; nacre 



