176 Ar t- 6. — M. Yokoyama: 



(»ne of the specimens measures 8,2 millim. in length, 7,8 

 millim. in height and 2,2 millim. in depth while the other 

 measures 7 millim. in length, 6,8 millim. in height and 2,2 

 millim. in depth. 



In my paper on the "Species of Limopsis found in the 

 Neogene of Eoshiba " (Jour. Geol. Soc. Tokyo, vol. XVII, no. 

 205, 1910), I described this species simply as Limopsis sp., ques- 

 tioning, Whether it is not L. ForskalU Adams (Proc. Zool. Soc. 

 Lond., 1862) from Oshima and Takanoshima, hut as the latter is 

 Without figures and said to possess unequal rihlets, I deem it 

 advisable to describe the present species as a new one. 



Fossil occurrence. — Miyata Zone (Kami-Miyata); Koshiba 

 Zone (Koshihn). Upper Musashino of Kazusa. 



Family Ledidae. 



Genus Led a, Schumacher. 



227. Leda ramsayi, Smith. 



Pl. XIX. Fig. 3. 



Leda ramsayi. Smith, Report on the Larnellibranchiata, Challenger Expedition, p. 241, 

 pl. XX, fig. 3, 3a. 



Two left valves. 



The shell is small, rather thin, compressed, transversely 

 elongated, strongly inequilateral, the anterior margin sharply 

 rounded, the posterior produced,,- rostrated and truncate at the 

 end. The ventral margin is broadly rounded, straight or even 

 slightly concave near the posterior end. On the surface there are 

 two ridges running from the beak to the upper and lower corner 

 of the truncated posterior margin. The sculpture consists of 

 strong concentric striae which are suddenly turned upward and 

 nearly at right angles on the flat or slightly concave space between 

 the two ridges. The area is concave, smooth and sharply bound- 

 ed by the upper ridges of the two valves. On the inner side of 

 the rostrate end there is a short transverse median ridge. The 

 teeth are numerous, close-set, the anterior row being decidedly 

 shorter than the posterior which occupies about two-thirds the 



