Quarterly Journal of Condiology. 127 



20. Paludina Japonica Martens. — "Very abundant in the 

 paddy-fields" at Yokohama. Most of the specimens 

 of this species have more or less malleation, one large 

 one having the entire surface strongly indented, the 

 body-whorl almost invariably displays an angulation or 

 obtuse carination around the middle, and sometimes 

 the two keels which encircle the upper whorls are 

 more or less apparent in the last above this central 

 angulation and in one example two or three remote 

 keels are faintly visible below it ; the operculum is of 

 a light-brown colour and very concave exteriorly in 

 the nuclear region. In the Cumingian collection there 

 is a single specimen having Japan affixed to it under 

 the name Vivipara Sdateri Frauenfeld. It is un- 

 doubtedly the same as the present species, but I am 

 not aware of Frauenfeld having ever published such 

 a species. P malleata Reeve is closely ailed to 

 Japonua, differing chiefly from it in having the whorls 

 rather more convex and the spiral carinations almost 

 obsolete : however they are just traceable and their 

 position is marked by series of spiral shallow punc- 

 tures, two in the upper whorls and three in the last, 

 as is the case in P. chinensis ; indeed it is scarcely 

 possible to distingush the two forms. 



21. Corbicula fluminea Midler. — "Abundant, eaten by the 

 natives " at Yokohama. 



Two of three specimens of this species are clothed 

 with a nearly black epidermis becoming greenish-olive 

 towards the margin of the valves ; the third is brown- 

 ish-olive. The interior is precisely the same as that 

 of Chinese specimens, being of a purplish colour, 

 darkest towards the edges and whitish in the umbonal 

 region. 



I fail to distinguish any specific differences from 

 this species in C. wyV/z/a//^ of Lamarck, and C. fliivia- 

 tilis of MuUer. 



