26 PROCEEDINGS OF THE ACADEMY OF [Jan., 



the periphery and one at the middle of the base. There are three 

 smaller cords between the upper and middle enlarged ones, and five 

 between the middle and the basal cord, which is largest of all. 

 Sometimes only the median and lower cords are enlarged. AVhorls 

 about 9, those of the spire angular at the lower third. Aperture ovate 

 with a short, deep anterior canal, the outer lip strengthened by a 

 moderately strong, rather narrow varix. 



Length 7.5, diam. 3.2 mm. , 



Length 8.3, diam. 3.7 mm. 



Hahajima, Ogasawara. Types Xo. 86,130. A. X. S. P., from Xo. 

 1,466 of ]\Ir. Hirase's collection. 



This peculiar little Cerite is very closely related to Bittluin oosimense 

 Watson, but differs by the number of whorls and the details of the 

 spiral sculpture, as may be seen on comparison Avith Watson's excellent 

 description and figure. It may perhaps be identical Avith Bitthim 

 scalatum Dimker. That species has been described too briefly to 

 decide with any certainty, and it has not been figured. The species 

 before me, however, is a true Cerithium, not a Bittium. 



RISSOID^. 

 Rissoa tokyoensis n. sp. PI. IV, fig. 40. 



Shell very small, regularly tapering from the last whorl, bright chest- 

 nut colored, the very thick peristome white. Sculpture of 8 spiral 

 cords on the last whorl, the upper four rather coarsely regularly tuber- 

 culate, those below less so, the lower two smooth. The spire and upper 

 portion of the last w^horl are indistincth' plicate longitudinally, the 

 tubercles on the spirals being at the points of intersection. W^horls 5, 

 convex, the first one smooth, the last whorl with a heavy white varix 

 behind the lip. Aperture oval, the outer lip sinuous, advanced belov.-. 



Length 2.3. diam. 1.2 mm. 



Tokyo Harbor. Types Xo. 70,910, A. X. S. P. 



Rissoa ogasawarana n. sp. PI. IV, fig. 41. 



Shell ovate, with a rather short, straightly conic spire. Cream- 

 white, with some indistinct brown spots below the suture. Sculpture 

 of rather small close longitudinal riblets, which on the last w'horl do 

 not pass below the periphery. These are crossed by about 11 spiral 

 cords on the last whorl. There are about 5 or bh slightly convex 

 whorls, the last one with a broad rounded but rather low varix a short 

 distance behind the thin outer lip. Aperture ovate, entire below. 



Length 2.2, diam. 1.2 mm. 



