296 ^^^- 1- — ^^- Yokoyauia : 



much rising at both ends, arcuated (at the least in front), devoid 

 of retusion. Dorsal areas large pouting, lanceolate; escutcheon 

 carinately defined, sublongitudinally grooved; lunule impressly 

 defined, its sulci finer. Interior bluish white, the front edge, in 

 adult example, most minutely crenulated ; hinge-margin broad, its 

 teeth rather numerous on both sides. Cartilage-pit small, tri- 

 angular. ' ' 



Although in our specimens the fine crenulations of the inner- 

 side of the front edge are not visible, still there is not the least 

 doubt of their belonging to Hanley's sj^ecies. 



The largest example is a right valve measuring 20 millim. in 

 length, 10.8 miilim. in height and 3.5 millim. in depth. It is 

 therefore somewliat larger than the one shown in Hanley's figure. 



Fossil occurrence. — Shisui (rare). Kamenari, Tega (not rare), 

 Shito (do). Oji and Shinagawa- 



Living. — Central Japan. China sea. 



329. Léeilu ratnsayi^ Smith. 



Leda mmsaiji. Smith, Report on Lamellibrauchiata, Challeug. Exp., p. 241, pi. XX, 

 fig. 3, 3a. Yokoyama, Foss. Miura Peuin., p. 176, pi. XIX, fig. 3. 



Three left valves, one of which attains 9.4 millm. in length, 5.4 

 millim. in height and 1.7 millim. in depth. Just as in the Lower 

 Musashino, the specimens are very rare. 



Fossil occurrence. — Shito. Lower Musashino of Miyata and 

 Koshiba. 



Living. — Off Sydney, New South Wales, in 950 fathoms 

 (Smith). Also Northern Japan (?) 



Genus YOtöIA, Möller. 



330. YoliTia Hotahilis, Yokoyama. 

 PI. XVII. Fig. 10. 



Yoldia arctica. Brauns, Geol. Env. Tokio, p. 47. p. VI, flg. 29. 

 Yoldia lanceolata. Toknuaga, Foss. Env. Tokyo, p. 57, pi. Ill, fig. 18. 



The shell is thin, compressed, transversely elongated, rounded 

 in front, rostrated and pointed behind, inequilateral, the anterior 

 side being much longer than the posterior (about 1.8 times as 



