﻿244 DESCRIPTIONS OF 



passing into black, except at the beaks and the basal margin, which are lightish 

 brown ; umbonial slope rounded ; cardinal teeth long, lamellar, oblique, double in the 

 right valve and single in the left ; lateral teeth long and somewhat curved, double in 

 the left and single in the right valve ; anterior cicatrices distinct, rather small ; 

 posterior cicatrices confluent ; dorsal cicatrices small and placed in the cavity of the 

 beaks, under the cardinal teeth ; cavity of the shell wide and rather deep ; cavity of 

 the beaks small and subangular ; nacre pure white and iridescent. 



Remarks. — A single specimen only was submitted to me by Mr. Cuming. In 

 outline it is very much the same as Unio spinosus (nobis) and is about the same size. 

 The teeth are very different, however, and the absence of anything like spines would 

 at once prevent its being confounded with that shell. It has somewhat the aspect of 

 IT. marginalis, Lam., but is not so transverse. It is perhaps most closely allied to IT. 

 lamellatus (nobis) from the Ganges. There are a few obscure rays near the beaks and 

 two well defined ones on the posterior slope. At the request of Mr. Cuming I have 

 named this after the gentleman who brought it from Ceylon to London. 



Unio Japanensis. PI. 36, fig. 123. 



Testa plicata, oblonga, antice subsulcata, subcouipressa, postice subbiangulata, valde insequilaterali ; 

 valvulis crassiusculis, antice paulisper crassioribus ; natibus prominulis ; epidermide tenebroso-fusca, 

 micante ; dentibus cardinalibus subgrandibus, elevatis, crenulatis, in utroque valvulo duplicibus ; 

 lateralibus longis subcurvisque ; margarita albS. et valde iridescente. 



Shell plicate, oblong, somewhat sulcate before, somewhat compressed, subbiangular 

 behind, very inequilateral ; valves rather thick, thicker before ; beaks slightly promi- 

 nent; epidermis dark brown, rather shining; cardinal teeth rather large, elevated, 

 crenulate, double in both valves ; lateral teeth long and somewhat curved ; nacre 

 white and very iridescent. 



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



Hab. — Japan. H. Cuming. 



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

 Diam. -6, Length 1*2, Breadth 1-9 inch. 



Shell plicate on the upper half of the disk, oblong, somewhat sulcate on the ante- 

 rior portion, subbiangular behind, rather compressed, very inequilateral; dorsal and 

 basal margins nearly parallel ; substance of the shell rather thick, slightly thicker 

 before ; beaks slightly prominent ; ligament rather long, thin, light brown ; epidermis 

 very dark brown, lighter on the lower part ; umbonial slope flattened ; cardinal teeth 

 rather large, elevated, crenulate, double in both valves ; lateral teeth long, somewhat 

 curved ; anterior cicatrices distinct, well impressed ; posterior cicatrices confluent, 

 rather indistinct ; dorsal cicatrices small and placed on the plate in the cavity of 

 the beaks ; cavity of the shell very shallow ; cavity of the beaks small and angular ; 

 nacre white and very iridescent. 



