﻿AN T D SPECIES OF THE FAMILY UNIONIDvE. 307 



medial and covered with folds ; ligament very short and rather thick ; epidermis 

 greenish brown, the folds being usually green, minutely striate over the whole disk ; 

 umbonial slope high and angular ; cardinal teeth thick, short and much divided : 

 lateral teeth thick, short, somewhat curved, doable in both valves and enlarged at the 

 posterior end ; anterior cicatrices distinct ; posterior cicatrices confluent ; dorsal 

 cicatrices placed on the underside of the posterior portion of the cardinal teeth ; cavity 

 of the shell rather deep ; cavity of the beaks rather deep and angular ; nacre bluish 

 white and iridescent. 



Remarks. — This species is very remarkable for its diminutive size. There were only 

 two specimens submitted to me by Mr. Haines, and I believe they are all he received. 

 They are nearly of the same size ; and if they be of normal dimensions, the species is 

 certainly the smallest I am acquainted with. It is nearest to U. crispatus, Gould, in 

 general appearance, being covered over with nearly the same kind of folds, which are 

 green like crispatus. In outline, however, it differs very much as well as in size, not 

 being more than one-third the breadth. The umbonial slope is also much more angular. 

 It might be suspected that it had been mistaken for a young crispatus, but on 

 comparison with a young crispatus before me, I find it flatter, less robust, with 

 smaller folds and more yellow. The minute strise over the disk are close and 

 lamellate, and are of a brownish color. The folds over the whole disk are strongly 

 marked, are green and disposed to run into angles, while the intermediate spaces are 

 yellowish. On the inside the folds are distinctly visible. 



Unio Brownii. PL 29, fig. 22. 



Testa lsevi, obovata, valde compressa, valde" insequilaterali ; valvulis subcrassis j natibus prominulis, costia 



divaricatis ; epidermide tenebroso-viridi, striata; dentibus cardinalibus submagnis, in utroque valvulo 



duplicibus; lateralibus lamellatis, sublongis curvisque ; margaritst alba. 



Shell smooth, obovate, very much compressed, very inequilateral ; valves rather 



thick ; beaks but little prominent, ribbed at the apex ; epidermis dark green, striate ; 



cardinal teeth rather large, double in both valves ; lateral teeth lamellar, rather long 



and curved ; nacre white. 



Proc. Acad. Nat. Sci. Vol. 8, p. 95. 

 Hab. — Mocha? Asia. Capt. George Brown. 

 My cabinet. 

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



Shell smooth, obovate, very much compressed, very inequilateral, elevated on the 

 posterior slope almost into a wing ; substance of the shell rather thick, thinner 

 behind ; beaks but a little prominent, with rather short divergent ribs at the apex ; 

 ligament short and very thin ; epidermis dark green, striate ; umbonial slope rounded 

 and very slightly raised ; cardinal teeth rather large, oblique, compressed, crenulate 



