202 Art - 6 - — M - Yokoyarna : 



mostly subequal on the apertural end, but alternately large and 

 small towards the apex. Interspaces generally wider than the 

 riblets. Striae of growth close, fine and sometimes very prominent. 

 Orifices nearly circular. 



This species is very much like D. vernedei Hanley (Sowerby, 

 Thesaurus, vol. Ill, Dentalium, p. 101, pi. 225, fig. 3) living in 

 our seas, but is readily distinguished by the interspaces being- 

 wider than the riblets, while the reverse is the case in the Hanley 

 species. 



Very frequent, especially in the Kanazawa, and Koshiba 

 Zones. 



Fossil occurrence. — Kamakura Zone (Urago); Kanazawa Zone 

 (Kanazawa and Nojima); Koshiba Zone (Koshiba); Naganuma 

 Zone (Kikközan, Iijima and Naganuma). 



Living. — Sandwich Islands at a depth of about 300 fathoms; 

 also Enoura in Suruga Bay, Central Japan. 



120. Dentalium weinkauffi, Dunkee. 

 Pl. VI. Figs. 19-21. 



Dentalium weinkauffi,. Ddnkek, Index Moll. Mar. Jap., p 153, pl. V, fig. 1. Pir.sBBY in 

 Tkyon's Man. Conch., vol. XVII, p. 40, pl. II, fig. 26. 



Dentalium cf. weinkauffi. Tokunaga, Poss. Env. Tokyo, p. 33, pl. II, fig. 16. 



This species is recognized by its well-curved shell, ribbed in 

 the apical portion, but smooth in its apertural portion, the ribs 

 gradually vanishing towards the latter. The number of ribs varies 

 according to the individuals, but are generally between twelve and 

 sixteen near the apical end, gradually increasing, however, towards 

 tho aperture. Frequent, but mostly broken. 



Fossil occurrence. — Miyata Zone (Mukaibatake in Shimo- 

 Miyata, and Kami-Miyata); Kanazawa Zone (Nojima); Koshiba 

 Zone (Koshiba); Naganuma Zone (Naganuma); Upper Musashino 

 of Musashi, Kazusa and Shimosa. 



Living. — Central Japan. 



