Fossils from the M iura Peninsula and its Immediate North. J09 



Two right valves one of which is 11 millim. long, 8 millim. 

 high .and 3 millim. deep, while the other is 9,5 millim. long, 6,5 

 millim. high and 2,5 millim. deep. 



This species is closely allied to a living one found in Sagami 

 Bay and probably identical with Basterotia recluzef A. Adams 

 (Ann. Mag. Nat. Hist., 1864, p. 301), unfigured). But the living- 

 form is less inequilateral and the difference of the heights of the 

 anterior and posterior ends less great. 



Fossil occurrence. — Yokosuka Zone (Otsu). 



Family Mesodesmatidae. 



Genu6 Ervilia, Türton. 



131. Ervilia otsuensis, Yokoyama. 



Pi. VII. Figs. 21, 22. 



Shell small, rather strong, moderately convex, ovately trian- 

 gular, equilateral; anterior border rounded, posterior obliquely 

 subtruncate, making a sharp angle with the broadly arcuate ven- 

 tral border. Surface concentrically and rather unequally grooved. 

 Beaks median, small but pointed. Anterior as well as posterior 

 cardinal tooth strong, with a longly triangular ligamental pit 

 between, whose posterior basal angle somewhat projects obliquely 

 downward. Palliai line distinct with sinus shallow, rapidly 

 narrowing and bluntly ending. One left and one right valve 

 apparently belonging to different individuals. 



The left valve measures 15 millim. in length, 12 millim. in 

 height and 3,5 millim. in depth. The right valve is slightly larger. 



Fossil occurrence. — Yokosuka Zone (Otsu). 

 Family Mactridae. 



Grenus Mactra. Linné. 



132. Mactra veneriformis, Deshayeb. 



Pl. VII Fig. 10. 



Mactra veneriformis. Deshayes, Proc. Zool. Soc. London, 1853, p. 15. Reeve, Conch. Ioon.^ 

 Mactra, pl, IX, fig. 78. Lischke, Jap, Meeresconch., I, p. 133, II, p. 121, pl. IX, fig, 7,8. Wein 1 



