Fossils from the Miura Peninsula and its Immediate North. \Q3 



210. Ostrea plicata, Chemnitz. 

 Pl. XVII. Figs. 1, 2, 3. 



Ostrea plicata. Chemnitz, Conch. Cab. VIII, p. 34, pl. 73, &g. 674, pl. 74, fig. 680. Reeve, 

 Conch. Icon, vol. XII, Ostrea, no. 63, pl. XXVII, fig. 63. ■ Danker, Index Moll., p. 249. 



Several ill preserved specimens. The upper as well as the 

 lower valve is depressed and only a little convex. The 

 general shape is ovate to oblong. The shell is either solid or 

 rather thin. On the surface there are generally a few radial folds 

 most distinct near the margin. On both sides of the hinge, the 

 inner margin is generally crenate or crenulate. The largest speci- 

 men which we have is only 65 millim. high. 



Fssil occurrence. — Yokosuka Zone (Ofcsu). 



Living. — Western Japan; China and East Indies. 



211. Ostrea musashiana, Yokoyama. 

 Pl XVI. Figs. 1-5. 



Shell moderate-sized, rather thin, generally ovate in outline, 

 but sometimes oval to oblong. Lower valve very convex with the 

 surface smooth and uneven, and marked with concentric valleys 

 and lines, the latter sometimes elevating themselves into short 

 laminae. In some specimens are 'developed a few radial plaits 

 which are, however, irregular and mostly indistinct. Left valve 

 unevenly flat. Frequent, 



The largest specimen measures a little over 60 millim. in 

 height. 



Fossil occurrence. — Yokosuka. Zone (Yokosuka); Koshiba 

 Zone (Köshiba). Upper Musashino of Shimosa. 



Family Arcidae. 



Genus JLrca, Lamarck. 



212. Area kobeltiana, Pilsbry. 



Pl. XVII. Fig. 4. 



Area kobeltiana. Pilsbry, New Jap. Mar. Moll., Pelecypoda, Proc. Acal. Nat. Sei. Phila«* 

 delphia, July, 1904, p. 559, pl. XL, figs. 16-19. 



