100 Art. 6.— M. Yokoyama:. 



Fossil occurrence. — Yokosuka Zone (Otsu and Yokosuka). 

 Living. — Central and Western Japan. 



116. Acmsea kuragiensis, Yokoyama. 

 Pl. VI. Fig. 9. 



Shell small, thin, conical, oval in outline, obtusely pointed at 

 apex which is somewhat anterior. Anterior as well as posterior 

 slope straight. The sculpture consists of very fine radiating lines 

 crossed by equally fine but distinct concentric attise, making them 

 appear finely crenulate. Length 7 millim., breadth 5 millim., 

 height 4 millim. A single specimen. 



This shell is closely allied to Acmœa triangularis (Carp.) 

 (Tryon's Manual, XIII, p. 20, pl. 7, figs. 74-78) and to Acmœa 

 patina Escu. var. ochracea Dall (Tryon's Man., loc. cit., pl. 9, 

 fig. 7-9), both from ( ,'alifornia. But our shell is distinguished 

 from them by crenulate radiating lines. 



Fossil occurrence. — Koshiba Zone (Koshiba). 



117. Acmaea nojimensis, Yokoyama. 

 Pl. VI. Fig. 11. 



Shell small, thin, conical, oblong in outline, with anterior 

 and posterior slopes somewhat convex and lateral surfaces some- 

 what flattened. Apex a little anterior, pointed. Surface with 

 fine radiating lines which are almost obsolete. Length 9 millim., 

 breadth 5 millim., height 5 millim. A single specimen. 



At first I took this for the same species as the preceding, but 

 the higher form and the non-crenulate. obsolete radiating lines 

 make it appear somewhat different. So at present I prefer to 

 treat it as a new species. It is not unlike Acmœa convins Dkr. 

 (Moll. Jap., p. 24, pl. Ill, fig. 19) which is, however, higher and 

 broader. 



Fossil occurrence. — Kanazawa Zone (Nojima). 



