70 Art. 6.— M. Yokoyama : 



The number of whorls must have been more than ten, but 

 the upper part of the shell being broken, it is not possible to tell 

 it exactly. The outer lip is also broken. The number of tuber^ 

 eles which are close together is about twenty on the body-whorl. 



This species is somewhat like Triforis cingidata Dunkee (Moll. 

 Jap., pi. II, fig. 1) which is, however, not tuberculated. Triforis 

 alveolatus A. Adams (Yoy. Samarang, pi. XI, fig. 30) also seems 

 to be related to this species, but its riblets are all of equal size. 



Fossil occurrence. — Yokosuka Zone (Otsu). Upper Musa- 

 shino of Kazusa. 



Living. — Central Japan. 



Family Tricholropidae. 



Genus Tric/totropis. Brode rip et Sowerby. 



67. Trichotropis planicostata, Yokoyama. 



Pl. IV. Fig. 6. 



►Shell small, thin, turbinate; whorls five, spire short and 

 acute, body-whorl very large; whorls of the spire convex, 

 shouldered, spirally costellated, costelUe fiat-topped, distant, four 

 in number, the upper two being weaker than the lower ones 

 and the shoulders being formed by the second one from below; 

 the surface above shoulders is obliquely ascending; on the body- 

 whorl the shoulder is not so distinct and the surface above it is 

 more horizontal, the surface below it is strongly convex with 

 seven distant and equal spiral costelhe down to the base, and an 

 interstitial spiral thread between the should er-costella and the one 

 below it. Interspaces between the costellaa partitioned off into 

 rectangular pits by more or less distant rounded longitudinal 

 threads which do not cross the costellaa. Aperture very large, 

 broadly oval, with peristome continuous and a faint indication of a 

 channel in front. Outer lip thin. Umbilicus small, deep. Height 

 11 millim. Diameter 9 millim. A single example. 



Fossil occurrence. — Koshiba Zone (Koshiba). 



