320 NEW UNIONID^ MELANID^, ETC., 



RemarTcs. — Mr. Wheatley presented me with two specimens of this species which 

 I had not before seen. One seems to be full grown, the other about one-third grown. 

 It is nearly allied to U. 'pxistulosus (nobis), and in outline is nearly the same, but 

 sphairicijis is more carinate on the posterior slope and is there obtusely angular. It 

 differs also in the form and number of the nodules, sphcericus having few, and those 

 small and not well pronounced. The specimens of pustulatus from the same habitat 

 have higher beaks and more well characterised nodules. There is also a difference in 

 the marks of growth, which are very much further apart in sphcericus. The color of 

 the epidermis is also different, in being of a dark chestnut-brown, which causes the 

 marginal edge to be a reddish line under the nacre. The nacre of the adult specimen 

 is beautifully white, with a disposition to a pinkish tinge. The young specimen has 

 a purplish nacre. It cannot be confounded with refulgens, herein described, although 

 it has nearly the same colored epidermis and nodules, resembling, in a measure, that 

 species, the nacre of which is brighter and purple. In regard to inflation they are 

 very different, refulgens being lenticular, while sphcericus is globose. Sphcericus has 

 a wide, shallow groove immediately before the umbonial slope. 



Unio Veracruzensis. pi. 52, fig. 133. 



Testa Irevi, elliptica, subcompressa, insequilaterali, postice obtuse angulata, antice rotundata ; valvulis 

 tenuibus ; natibus prominulis ; epidermide tenebroso-fusca, radiata politaque ; dentibus cardinali- 

 bus parvis, compressis, crenulatis, in utroque valvule duplicibus ; lateralibus longis, rectis lamel- 

 latisque ; margarita cserulea et valde iridescente. 



Shell smooth, elliptical, somewhat compressed, inequilateral ; obtusely angular 

 behind, rounded before ; valves thin ; beaks slightly prominent ; epidermis dark 

 brown, radiated and polished ; cardinal teeth small, compressed, crenulate and double 

 in both valves; lateral teeth long, straight and lamellar; nacre bluish and very 

 iridescent. 



Proc. Acad. Nat. Sci. 1868, p. 150. 



^-a&.—Vera Cruz, G. Strebel, M. D. 



Cabinet of Smithsonian Institution. 

 Diam. -4, Length -7, Breadth 1*2 inch. 



Shell smooth, elliptical, somewhat compressed, inequilateral, obtusely angular 

 behind, rounded before ; substance of the shell thin ; beaks a little prominent, very 

 slightly inflated ; ligament very short, thin and light brown ; epidermis dark brown, 

 radiated all over and polished; umbonial slope low and rounded; posterior slope 

 slightly raised and has two impressed lines in each valve ; cardinal teeth small, com- 

 pressed, crenulate and double in both valves ; lateral teeth long, straight and double 

 in both valves; anterior cicatrices distinct, small and slightly impressed; posterior 



