222 ON THE NAIADES, 



Cyrena Woodiana. Plate XVIII. fig. 55. 



TestA subtrigond, siibinflatd, micante, subsequilaterali, transversim rugatd ; val- 

 vitlis crassis ; natibus magnis et rotundatis ; dentibus cardinalibus sub-bijidis, 

 lateralibiis longis, serratis, rectisque; margaritd alba. 



Shell subti'iangular, somewhat inflated, shining, nearly equilateral, transversely wrin- 

 kled ; valves thick ; beaks large and rounded ; cardinal teeth disposed to be biiid ; late- 

 ral teeth long, straight, serrulate ; nacre white. 



Hab. Canton. W. W. Wood. 



My Cabinet. 

 Diam. 1 -4, Length 2-4, Breadth 2-9 inches. 



Shell siibtriangular, obtusely angular behind, somewhat inflated, 

 shining, nearly equilateral, transversely and rather largely wrinkled ; 

 substance of the shell thick ; beaks large, rounded, not very approxi- 

 mate ; ligament rather short and thick ; epidermis blackish brown, 

 polished, except on posterior slope; wrinkles larger near to the margin ; 

 cardinal teeth disposed to be bifid ; lateral teeth long, straight, serrulate ; 

 cicatrices scarcely perceptible ; cavity of the shell deep ; cavity of the 

 beaks angular ; nacre white. 



Remarks. — In the intenseness of colour of the epidermis, and its high 

 polish, this species differs from any I am acquainted with. It is more 

 inflated and less rotund than the rotiindata herein described. Its 

 lateral teeth are longer and not so minutely serrulate. In its triangular 

 form it resembles the C. papua (Lesson). The nacre has not the 

 clear white usual in this genus. In this specimen, below the palleal 

 impression, it is yellowish white. 



Mr Wood, to whose great kindness I owe this fine and interesting 

 species, informed me he procured it from a boat on the river below 

 Canton, it having been fished up by accident, when the fishermen 

 were engaged in catching other shell fish. Owing the possession of it 

 to him, I with great pleasure dedicate it to him. 



