J04 ' -^ r t' 8. — M. Yokoyama : 



Fossil occurrence. — Miyata Zone (Nagai): Yokosuka Zune 

 (Yokosuka); Naganuma Zone (Nagaimma); Upper Musashino of 

 Musashi and Shimosa. 



Living. ■ — Central and Western Japan. 



Genus (Jadtflus. I'hilippi. 



123. Cadulus gordonis, Yokoyama. 



Pl. VI. Fig. 25, 26. 



Shell small, slender, slightly curved, smooth, obtusely 

 angulated just behind the aperture, whence it narrows both 

 anteriorly and posteriorly, but very quickly anteriorly and very 

 gradually posteriorly. Aperture circular, straight. No slit. 

 Length 7 millim. greatest diameter 1 millim., posterior diameter 

 0,8 millim. Two specimens, one of which is broken. 



This species is closely allied to Cadulus acus I) all (Tuyon's 

 Manual, XVII, p. 191, pl. 36, tig. 27) from the West Indies in 

 which, however, the shell is more pointed and the aperture some- 

 what oblique. 



Fossil occurrence. — Miyata Zone (Nagai); Naganuma Zone 

 (Naganuma). 



Class Lamellibranchiata. 



Order Teleodesmacea. 



Family Pholadidae. 



Genus F/tolas, Linné. 



124. Pholas fragilis, Sowerby. 



Pl. VI. Fig. 29. 



Pholas fragilis. Sowerby, Thes. Conch., vol. II, p. 488, pl. 108, figs. 92, 93. Lischke, Jap. 

 Meeresconch., I, p. 143. 



Barnea fragilis. Ddnkeb, Index Moll., p. 170. 



The shell is thin, fragile, transversely elongated, with the 

 anterior ventral margin widely notched and gaping, and the 

 posterior margin roundly pointed. The sculpture consists of 



