On Japanese Species of Corbicula. 



BY 



Henry A. Pilsbry, Sc. D. 



{With Plate VU). 



The first records of Corbicula, from Japan were by Temple Prime, in 

 18Ó4, who described two species, C. h ana and C. japonica. In 1878 Dr. 

 O. Reinhardt reviewed the Japanese species in a valuable paper, describ- 

 ing several new forms. Later, they were included by Clessin in his mono- 

 graph of the family, and by Kobelt in his useful Fauna, 1879. Professor 

 von Martens (1877), and the present writer (1901) have also contributed to 

 the literature of the group. 



Specific differences in Corbicula are not strongly developed, though 

 a great deal of local differentiation is evidently in progress, so that one 

 can almost say that every lot gathered has its own minor peculiarities. In 

 this multitude of forms differing by slight, often hardly definable, charac- 

 ters, it is difficult to define conventional species. As in the holarctic 

 Pisidia, the modifications have in a large degree not reached the 

 " specific " stage. Yet by taking account of only their more important 

 features, the known Japanese forms may be grouped into less than a dozen 

 reasonably well-characterized species, though it cannot be claimed that 

 every specimen or form which may be encountered can easily be referred 

 to one or other of them.* 



The following descriptions are based chiefly upon a series of 

 specimens from the Imperial Household Museum, furnished by Mr. T. 

 Iwakawa ; but I have also studied specimens presented to the Academy 

 of Natural Sciences by T. Prime, Y. Hirase and others. 



* In dealing with the Chinese species. Père Heude has attempted to name every local form, 

 a task I believe to be practically impossible, aud if accomplished the result would be absolutely 

 useless to any other zoologist from the impossibility of agani recognizing the forms. 



