74 Art. 1. — M. Yokoyama : 



somewhat convex in the lower two-thirds, spirally grooved ; grooves 

 three, dividing the surface of the whorls into four parts of which 

 the upper three are nearl}' equal in hreadth, while the lowest is a 

 little narrower. Periphery subangulate. Base with two spiral 

 grooves near the periphery. Aperture rhomboidal. Outer lip thin 

 Canal short, narrow^, bent sideward as well as backward. Height 

 11.5 milhm. Diameter 2.5 millim. 



In one of the specimens, which are not at all rare, the upper 

 portion of the spire is slightly curved, and in young ones the Avhorls 

 may be all nearly flat. 



Fossil occurrence. — Shito. 



Family Triforidae. 



Genus TKIFOKIS, Deshayes. 



9». Ti'iforis ofsnensis, Yokoyama. 



PI. III. Fig. 16. 



Triforis otsiiensis. Yokoyama, Foss. Miura Penin., p. 69, pi. IV, fig. 11. 



This species which I founded on a single specimen from the 

 Lower Musashino of Yokosuka is represented by four specimens, 

 in two of which the apex is not preserved. The whorls number 

 about twelve, the first three being embryonal. The middle spiral 

 rib of the body-whorl which is equal in size to the other two in the 

 specimens of Yokosuka is in the present ones always more or less 

 weak, as on the preceding whorls. The aperture is a rounded 

 square. Height about 5.5 millim. Diameter 1.5 milhm. 



Fossil occurrence. — Shito. Lower Musashino of YV)kosuka. 

 Living. — Central Japan. 



94. Tt-i forts mutfiffj/rafa, Yokoyama. 

 PI. V. Fig. 5. 



A single specimen of a small, subulate, subcylindric shell with 

 the apex a little broken, but still with eighteen wliorls preserved. 

 Its height is 13 millim. and its diameter 2.8 millim. The whorls 

 are flat and triseriately gi-anose with interspaces narrower than the 



