Fossils from the Upper Musashino of Kazusa and Shimosa. ]^72' 



the ventral is broadly arched. The valves are very unequal; while 

 the right is moderately convex, the left is either flat or somewhat 

 concave. Moreover, the right valve has a blunt posterior keel on 

 the surface. The sculpture is the same in both valves, consisting 

 of coarse concentric undulations. Behind the beaks there is an 

 elongated areal excavation bounded by more or less distinct edges. 

 The anterior muscular impression is longly pear-shaped and curved 

 inward, while the posterior is ovate and upright. Palliai sinus 

 shallow, rounded, somewhat ascending. Length 17. :2 millim. 

 Height 14.3 millim. Thickness 5.4 millim. 



The variation in form lies chiefly in the degree of rotundity of 

 the anterior end. 



Fossil occurrence. — Otake (common), Tega (rather common), 

 Shisui, Kamenari, Kioroshi, Sliito (very common). C)ji and. 

 Shinagawa, 



Living. — Western Japan. 



277. Mfßodova reeviaiia, Smith. 



PI. XIV. Figs. 8, 11. 



Myodora reedana. Pilsbry, New Jap. Mar. Moll., Pelecyp., Proc. Acad. Nat. Sei. Phil., 

 July 1904, p, 558, pi. XLI, figs. 7-10. Yokoyama, Foss. Miura Penin., p. 143, pi. 

 XI, figs. 12, 13. 



This species has already been described b}^ me from the 

 Lower Musashino in the work above cited. 



Fossil occurrence. — Otake, Shisui, Shito (rather common.) 

 Lower Musashino of Miyata and Koshiba. 



Living. — Western Japan. China. 



Family Thraciidae. 



Genus THHACIA, Leach. 



278, HiracUi papyraeea, (Poh). 

 PI-, XIV. Fig. 12. 



Thracia papyraeea. Homes, Foss. Moll. Tert. Beck. v. Wien, II, p. 49, pi. V, fig. 3. 



Wood, Crag Moll, Biv. Suppl, p. 156. Nyst. Coiicb. Terr. Tert. Belg., d. 215, 



pi. XXVII, fig. 6. 

 Odoncincta papyraeea. Da Costa, Cat. Syst. Test, Sicil., p. 23, pi. II, figs. 1-4. 

 Tellina papyraeea. Poli, Test. Utr. Sicil., I, p. 43, pi. XV, figs. 14-18. 



