﻿EXOTIC UNIONIDJE. 239 



young have a well-defined anterior lamellar tooth and a distinct posterior raised line, 

 which, in the left valve, is slightly divided. This is so marked in these young 

 specimens, that one would hardly hesitate to place them among the Uniones if we had 

 not the adults, which have scarcely a vestige of the elevated lines on the dorsal 



Unio Sumatrensis. PI.. 34, fig.. 118.. 



Testa plicata, subtriangulari, subventricosa, postice subbiangulata, inaequilaterali; valvulis subcrassis ; 

 natibus subprominentibus; epidermide mioante, luteo-oliva, postice virenti ; dentibus cardinalibus 

 lamellatis, compressis, obliquis, in utroque valvulo duplieibus ; lateralibus subbrevibus curvisque ; 

 margarita alba et irideseente. 



Shell plicate, subtriangular, rather inflated, subbiangular behind, inequilateral ; 

 valves rather thick; beaks somewhat prominent; epidermis shining, yellowish olive, 

 greenish behind; cardinal teeth lamellar, compressed, oblique and double in both 

 valves ; lateral teeth rather short and curved; nacre white and iridescent. 

 Unio Sumatrensis, Lea. Proc. Acad. Nat. Sci., 1859, p. 153. 



Hob. — Sumatra. H. Cuming. 



My cabinet and cabinets of Mr. Cuming and C. M. Wheatley. 

 Diam. -9, Length l'l, Breadth 1-8 inches. 



Shell with very small folds nearly over the whole disk, subtriangular, rather 

 inflated, subbiangular behind, inequilateral; substance of the shell rather thick; 

 beaks somewhat prominent; ligament short, thin and bright brown ; epidermis shining, 

 yellowish olive, subsulcate, without rays; umbonial slope raised and rounded ; pos- 

 terior slope wide, with very small oblique, nearly parallel folds; cardinal teeth 

 lamellar, compressed, very oblique, nearly straight and double in both valves; lateral 

 teeth rather short and curved ; anterior cicatrices confluent; posterior cicatrices con- 

 fluent; dorsal cicatrices placed on the under side of the posterior portion of the 

 cardinal teeth ; cavity of the shell deep and rounded ; cavity of the beaks rather 

 deep and obtusely angular; nacre white and iridescent. 



Remarks. — In outline and color this species is allied to U. Javanus (nobis), but it 

 is more triangular, more inflated and has small irregular folds over the whole disk. 

 It is greatly to be regretted to be obliged to make diagnoses from single specimens as is 

 necessary in many of these rare foreign species. When many and more perfect 

 specimens are obtained very essentially different characters may be observed. 



Anodonta gracilis. PI. 34, fig. 119. 



Testa losvi, transversa, subcylindraceS,, valde" insequilaterali ; valvulis tenuibus ; natibus subprominentibus 

 ad apices undulatis : epidermide flavescente, striata; margarita vel alba vel perpurea et valde" 

 irideseente. 



Shell smooth, transverse, subcylindrical, very inequilateral ; valves thin ; beaks a 



61 



