Fossils from the Upper Musashino of Kazusa and Shimosa. 71 



Family Cerilhiidae. 



Genus C'ERITHIl'W, Aclanson. 



87. CerifhiutH, (C'lnra) Jioehi, Philippi. 



PI. III. Fig. 13. 



Cerithitim kochi. Philippi, Abbild, n. Beschr., Ill, Ceritbium, p. 2 (14), pi. I, fig. 3. 



Liscbke, Jap. Meerescoucb., I, p. 76, III, p. 49. Tokunaga, Foss. Env. Tokio, p. 



24, pi. I, fig. 49. 

 Cerithiiim (Vertagits) kochi. Tryon, Man. Coucb., IX, pi. 28, figs. 48, 49. 

 Vertarjus kocliii. Dnnker, Ind. Moll., p. 108. 

 Clava kochi. Pilsbry, Cat., p. 56. 



Two specimen^^ of a narrowly tiirrete shell. Tlie wliorls are 

 flat and ornamented witli seven close, flat, spiral ribs which are 

 alternate]}^ large and small. The uppermost rib which is a small- 

 er one is often rather indistinct, being close to the suture. The 

 larger ribs are all tuberculate, while the smaller are either smooth 

 or only indistinctly tuberculate. Columella-fold single, weak, and 

 oblique, but towards the interior liigh and strong. Height 35 

 millim. Diameter lU millim. 



Fossil occurrence. — Otake. Shinagawa in Mu.sashi. 



Living. — Central and Western Japan. East Coast of Africa. 



Genus POTA^IIDES, Brongniart. 



88. Pofmnidea {Tytnintnotonos) fluviafilis, 



(Postiez et jMichand). 



Potamides {Tym})anotonos)ßiiviatilis. Pilsbry, Cat., p. 57. Tokunaga, Foss. Env. Tokyo, 

 p. 25, pi. I, fig. 52. Yokoyama, Foss. Minra Penin., p. 68, pi. IV, fig. 14. 



Potamides fliiviatilis. Liscbke, Jap. Meeresconcli., I, p. 76, IT, p. 69. 



Tympanotonos fluviatilis. Dnnker, lud. Moll., p. 110. 



Cerithium ßiiviatile. Postiez et Midland, Cat. Moll. Donai, p. 363, pi. 31, figs. 19, 20. 

 Sowerby, Tbe.s. Concb., 11, p. 891, pi. 186, figs. 295, 298. 



Potmiiides cf. i)icisiis. Tokunaga, Foss. Env. Tokyo, p. 26, pi. I, fig. 53. 



This shell is characterized by tlat whorls on which there are 

 three flat distant ribs. These ribs are furnished with tubercles 

 which form longitudinal rows linked together by a thread. 



