﻿[289] 



ART. XIX. — Descriptions of Exotic Genera and species of the family Unionid^e. 



By Isaac Lea, LL. D, 

 Unio Hainesianus. PI. 21, fig. 1. 



Testa alata, tevi, subrotundata, subinflata, valde inasquilaterali, valvulis crassis; natibus promincntibus, 

 angularis; epidermide luteo-fusca; dentibus cardinalibus crassis, creuulatis elevatisque; lateralibus 

 longis, crassis subcurvisque ; margarita alba et iridescente. 



Shell winged, smooth, subrotund, somewhat inflated and very inequilateral ; valves 

 thick ; beaks rather prominent and angular ; epidermis yellowish brown ; cardinal 

 teeth thick, crenulate and elevated ; lateral teeth long, thick and somewhat curved ; 

 nacre white and iridescent. 



Proc. Acad. Nat. Sci. Vol. 8, p. 92. 



Hab.—Siam. S. R. House, M. D. 



My cabinet and cabinet of W. A. Haines, New York. 

 Diam. 2*3, Length 4-5, Breadth 5-6 inches. 



Shell winged behind, smooth, subrotund, rather inflated and very inequilateral, 

 rounded before and behind ; substance of the shell thick, thinner behind ; beaks rather 

 prominent, angular, and marked on the anterior portion with a line of small folds ; 

 ligament long, thick and concealed ; epidermis yellowish brown, and apparently with- 

 out rays ; umbonial slope without any elevation : marks of growth very distant ; car- 

 dinal teeth thick, crenulate, conical and double in both valves ; lateral teeth long, 

 thick, lamellar and somewhat curved, the bifid end short, and the area between this 

 and the cardinal tooth smooth and arched ; anterior cicatrices distinct and deeply 

 impressed ; posterior cicatrices confluent ; dorsal cicatrices in a long row from the 

 centre of the cavity of the beak ; palleal cicatrix deeply impressed ; cavity of the shell 

 rather deep ; cavity of the beaks shallow and angular ; nacre white and iridescent. 



Remarks. — There are two specimens only of this fine species among the shells from 



Mr. Haines, procured through Dr. House from Siam. I dedicate it to Mr. Haines 



with great pleasure. In outline it is close to U. superbus, (nobis,) but is more rotund. 



It is more shallow in the cavity, much thicker in the anterior portion, and in the 



teeth they differ much. The cardinal teeth of U. superbus are long and lamellar, 



while in Hainesianus they are short, thick and conical. The nacre is not so pearly in 



the latter. In outline and form of the teeth it approaches Unio Paranensis, (nobis,) 



also, but the lateral teeth are not so long, and the upper section of the double tooth 



74 



