406 PROCEEDINGS OF THE ACADEMY OF [July, 



these his B. chinensis seems to me to be typical B. striatula, while B. 

 spiralis is a more slender, B. scalaris a stouter form, perhaps not 

 more than varietally distinct. B. striatula Bens, of Heude is a 

 strongly keeled form, certainly not the typical striatula of Benson. 

 His identification of it was possibly due to a remark of von Mar- 

 tens in Jahrb. D. Mai. Ges. y II, 1875, p. 133. 



I have no great faith in the distinctness of any of these sup- 

 posed species ; but if several Chinese forms are to be distinguished, 

 the Japanese shells evidently deserve at least varietal rank. They 

 are nearer B. striatula Heude non Benson than to any other of 

 the Chinese varieties. 



SPHJBBIID^B. 

 Sphaerium inutilis n. sp. 



Shell oval, much inflated, thin, equilateral, grayish-brown, with 

 a pale basal zone; glossy, minutely striate; anterior end curved 

 in a semicircle; posterior end a little more obtuse, though still 

 well curved. Beaks small, projecting, " calyculate," or tipped 

 witn a distinctly demarked protoconch. Interior bluish-white; 

 cardinal teeth subobsolete, extremely compressed, parallel, with the 

 hinge-line, divided in the right valve, single in the left; lateral 

 teeth moderately strong, double in the right, single in the left 

 valve. Length 10, alt. 8.6, diam. 6.2 mm. 



Nishigo, Uzen (Mr. Y. Hirase). 



r ^ Three species of Sphcerium are now known from Japan : S. 

 japonicum Westerlund, 18 S. heterodon Pilsbry, 19 and the present 

 species. All belong to the subgenus Calyeulina. S. japonicum is 

 an elongate " subtrapeziform " species. S. inutilis differs from 

 S. heterodon in having higher beaks, a more curved hinge-line, 

 rounded ends and it is more globose. 



No Pisidium or Cyrena is yet known from Japan proper, although 

 the latter genus occurs in the middle group of the Loo Choo 

 Islands. 



CYRENID^E. 

 Corbicula sadoensis n. sp. 



Shell triangular-oval, moderately inflated, solid; glossy, nearly 

 black in adults, sculptured with very close, irregularly raised and 



18 Calyeulina japonica West., NacWbl. d. D. Malak. Ges., 1883, p. 58 

 (April); Vega Exp., IV, p. 216, PL 6, fig. 31, from Jokogava, near Tokyo. 



19 Gatal. Mar. Moll. Jap., p. 159, PL 3, figs. 15, 16, 17, from Hizen, in 

 Kiusiu. 



