1426 ANODONTITES 



periostracum. or caused by tlie fore and middle parts of the 

 length being more worn than the hinder part, it is impossible 

 to tell. I know of no other Anodonta or Glaharis with similar 

 structure; the general form and solidity of the shell, as well 

 as the well-marked, dull, (lustreless), marginal zone, prove 

 that it belongs to the South American group of Anodonta late- 

 marginata Lea." 



This species may be only a form of inccqnivah'is, from which 

 it seems to differ mostly in its larger size and the greater so- 

 lidity of its shell. 



Anodontites TF.HUANTEPECCNSis (Crosse and Fischer). 



"Shell inequilateral, oval, slightly inflated, quite solid, cov- 

 ered with a greenish-brown epidermis, without rays, with fine, 

 concentric striae, which become sublamellose posteriorly and 

 near the ventral margin ; anterior side curved ; posterior side 

 obliquely and obtusely subtruncate ; ventral margin regularly 

 curved ; dorsal margin nearly straight, slightly ascending be- 

 hind the beaks, which are small and eroded ; dorsal slope some- 

 what compressed and obscurely bounded by an obliquely de- 

 scending depression. Nacre bluish-white and iridescent ; ad- 

 ductor muscular impressions superficial. Ligament narrow. 



Length 56, height 37. diam. 19.5 mm." (Crosse and Fisch- 

 er). 



Type locality, Cacoprieto, Isthmus of Tehuantepec, State 

 of Oajaca, Mexico. 

 Anodonta tchuantcpcccnsis Crosse and Fischer, Jl. Con., 



XLL 1893, p. 32. — Fischer and Crosse, Miss. Sci., H, 1894, 



p. 526, pi. LXX, figs. I-Iff. 

 Glabaris tehuantepecensis Simpson, Syn., 1900, p. 933. 



"We have seen only a single specimen of this species, which 

 is distinguished from its allied forms by its regularly oval 

 shape and its rather solid shell." 



Anodontites trmttwinianus (^Lea). 



Shell elliptic rhomboid, scarcely subsolid, convex or subin- 

 flated, inequilateral; beaks moderately full and elevated; pos- 

 terior ridge rounded, ending in a Munt point near the base of 



