,j^26 -^^*- ^- — ^- Yokoyama : 



This sliell looks like Corbiila striata Walther and Boys 

 (Wood, Crag Moll., II, Bivalves, p. 274, pi. XXX, fig. 3) from 

 .the English Crag, although more quadrate in shape. 



Fossil occurrence. — Shito. 



Family Myacidae. 



Genus CKYPTO-^IYA, Conrad. 



loi. Crypfointja btisGetisis, Yokoyama. 



PI. VII. Figs. 1, 2. 



Shell small, thin, transversely elliptical, convex, nearly 

 equilateral, rounded in front, ohliquely truncate behind, the trun- 

 cated border forming tolerably sharp angles both above and below. 

 Antero-dorsal margin arched, postero-dorsal nearly straight, 

 ventral broadly arcuate. Surface smooth, with beaks small, a 

 sharp edge running from them to the postero-ventral corner, 

 behind which the surface is slightly concave. Left valve with a 

 triangular ligamental spoon and a tooth behind it. Anterior 

 muscular impression elongated -fusiform, somewhat bent in the 

 middle, posterior short-fusiform. Palliai line simple. 



Specimens are rare. The largest we have is a left valve 18.5 

 millim. in length, 11 millim. in height and 3 milhm. in depth. 

 The next largest is a right valve 17.5 millim. in length, 11 milhm. 

 in height and 3-5 millim. in depth. 



This species is closely akin to Cryptomya eU'iptica Adams 

 (Dunker, Ind. Moll, p. 178, pi. VII, figs. 17-19), but lacks the 

 radial striations of the latter. 



Fossil occurrence. — Otake, Kamenari. Oji in Musashi. 



Living. — Central Japan. 



Family Maclridse. 



Genus MA€TliA, Linné. 



193. Macfè'a sulcataria, Desliayes. 



PL VIT. Fig. 6. 



Mactra sulcataria. Deshayes, Proc. Zool. Soc. Loudon, 1855, p. 15. Eeeve, Conch. 

 Icon., Mactra, sp. 5. Schreuck, Moll. Amur), u. d. nordjap. Meeres, p. 570, pi. 



