136 Art. 1.— M. Yokoyama : 



Genns SOLECTRTUS, Blainville. 

 20S. Solecui'fns *livaricafns, (Lischke). 



Sol ec art us dimricatus. Clessiu iu Mart. n. Ciiem. Syst. Conch. Cab., XI, pt. 3, p. 87, 

 pi. 21, fig, 4. Yokoyama, Foss. Minra Peinn., p. 112, pi. YII, fig. 14. 



Miicha dicaricata. Lischke, Jap. Meeresconch., I, p. 142, pi. X, figs. 1, 2. Tokuuaga, 

 Foss. Env. Tokyo, p. 36, pi. 11, fig. 20. 



Soleciirtus {Macha) divaricatus. Pilsbry, Cat., p. 121. 



This shell fiivt described and figured by Lischke is pretty 

 frequent as a fossil. It is readily recognized by its transversely 

 elongato-oblong form with distant, impressed, radiating lines on 

 the surface. 



Fossil occurrence. — Otake (pretty frequent), Tega, Shito. 

 Oji m Musashi. Lower Musashino of Yokosuka. 



Living. — Central and Western .Japan. 



Genns l>OXAX, Linné. 



20Ö. Donna' ittfforadiftttis, Reeve. 



PI. IX. Fig. 8, 9. 



Donax introradiatus. Eeeve, Couch. Icon., Donax, pi. IX, fig. 65. Eömer in Syst. 

 Conch. Cab., X, part 3, p. 75, pi. XIII, figs. 5-8. 



A very young shell with both valves perfect. It is charac- 

 terized by radiating strise Avhich are also visible from inside. In 

 the anterior half of the shell, these stride are rather indistinct. 

 The posterior slope of the shell-margin is convex, with a somewhat 

 wing-like projection. Ventral margin crenulate within. Length 

 4.2 millim. Height 31 millim. Thickness 2.4 millim. 



Fossil occurrence. — Tega. 



Living. — Central Japan. 



Family Psammoblidae. 



Genns PSA.-?fl.'?îOBIA, Lamarck. 



210. Psatntnob ia ka^^nsensis, Yokoyama. 



PL IX. Fig. 4. 



Two left valves whic]^, however, are quite characteristic. 



