Fossils from the Upper Musashino of Kazusa and Shimosa. 127 



liXIII, figs. 1, 2. Lischke, Jap. Meeresconch., I, p. 133. Pilsbry, Cat., p. 

 118. Tokunaga, Foss. Env. Tokyo, p. 40, pi. II, fig. 26. 

 Trigonella siilcataria. Dunker, Intl. Moll., p. 182. 



This rather thin-shelled species is easily recognized by its 

 ovately triangular shape, longer than high, somewhat equilateral 

 and with both extremities rounded, posterior somewhat more 

 sharply than anterior. Convexity moderate. The surface is 

 concentrically but unequally grooved. Lunula and area hardly 

 developed. 



The shell attains a large size, the largest in our collection 

 being 78 millim. in length and 67 millim. in height. 



Fossil occurrence. — Otake (in thousands), Kamenari 

 (frequent), Kioroshi (do), Shisui (do), Tega (do), Shito. Oji and 

 Shinagawa in Musashi. 



Living. — Northern to Western Japan. North China. Possiet 

 Bay (near Vladivostok). 



10». Jftaefra veneriforuiis, Deshayes. 



M%^tra vmeriformis. Desbayes, Proc. Zool, Soc. London, 1853, p. 15. Pieeve, Conch. 

 Icon., Mactra, pi. IX, fig. 78. Lischke, Jap. Meeresconch., I, p. 133, II, p. 121, 

 pi. IX, figs. 7, 8. Brauns, Geol. Env. Tokio, p. 38, pi. IV, fig. 17. Tokunaga, Foss. 

 Env. Tokyo, p. 40. Yokoyama, Foss. Miura Penin., p. 109, pi. VIII, fig. 10. 



Trigonella veneriformis. Dunker, Ind. Moll., p. 182. 



This shell, which is found in thousands in the seas near Tokyo, 

 is represented only by two specimens, a left and a right valve. 

 Its rarit}^ as a fossil in general is quite noteworthy. When 

 compared with the preceding species, it is usually somewhat 

 smaller, but higher and more inflated. 



Fossil occurrence. — Otake, Tega. Lower Musashino of 

 Yokosuka. 



Living. — Northern to Western Japan. 



1S4. Jttactrei ovetlina, Lamarck. 

 PI. VII. Fig. 12, 13. 



Mactra ovalina. Lamarck, Hist. Nat,, 2d. Ed., VI, p. 104. Pteeve, Conch. Icon., 

 Mactra, pi. XIV, fig. 66. Mart. Chemn. Syst. Conch. Cab., Mactra, p. 69, pi, 

 XXV, figs. 1, la, pi. XXVIII, fig. 3. 



