Fossils from the M iura Peninsula and its Immediate North. ]Q3 



121. Dentalium octogonum, Lamarck. 

 Pl. VI. Figs. 22, 23, 24. 



Dentalium octogonum. Lamarck, Anim. sans Vert., V, p. 344. Lischke, Jap. Meeres- 

 conch., II, p. 103, TTJ, p. 75, pl. V, figs. 1-8. Dünker, Moll. Mar. Jap., p. 153. Schrenck, 

 Moll. Aiuurl. u. d. Nordjap. Meeres, p. 381. Brauns, Geol. En vir. Tokio, p. 95. Tokdnaga, 

 Foss. Env. Tokyo, p. 33, pl. II, fig. 15. 



Dentalium Oct mgulatum. Donovan, Nat. Hist. Brit., Shells, V, pl. 162. Pilsbry in 

 Tryon's Man. Conch., XVII, p. 16, pl. II, figs. 16 18, 22. 



Dentalium hexaponum. ' Gould, Proc. Bost. Soc. Nat. Hist., vol. VII, p. 166. Otia Conch., 

 p. 119. Sowerbv, Thes. Conch., Ill, p. 103, pl. 223, fig. 10. Lischke, Jap. Meeresconch., Ill, 

 p. 74, pl. V, figs. 4, 5. and var., figs. 6, 7. Pilsbry in:TRYON - s Man. Conch., XVII, p. 18, pl. 

 LT, figs. 20, 21, and var. 23, 24, 27, 28. 



Dentalium sexcostatum. Sowerby, Thes., Ill, p. 103. pl. 223, fig. 11. 



The shells of a Dentalium here figured have heen formerly 

 described as two distinct species under the names of octogonum 

 and hexagonum. Hat the number of ribs on which the above 

 distinction is based is very variable; it varies between six and 

 nine. Fig. 22 has six, but fig. 23 has seven and fig. 24 nine. 

 The interstitial riblets or strife are also variable in number. In 

 some interspaces there are none, in others there are three to six. 

 They are equal or subequal, equidistant or inequidistant. 



Frequent. 



Fossil occurrence. — Miyata Zone (Nagai); Yokosuka Zone 

 (Yokosuka and Otsu); Naganuma Zone (Naganuma); Upper 

 Musashino of Musashi, Kazusa and Shimosa. 



Living. — Northern, ('entrai and Western Japan; China; 

 Australia; ( îeylon. 



122. Dentalium edoense, Tokünaga. 

 Pl. VI. Fig. 28. 



Dentalium aloen*e. Tokunaga, Foss. Envir. Tokyo, p. 34, pl. II, fig. 17. 



Several fragments of a small, slender, tubular shell, hardly 

 1,5 millim. in the greatest diameter, well curved but with 

 curvature not always quite regular, and with surface smooth, 

 glossy, and more or less uneven in some parts seem to be identical 

 with the one described by Tokuxaga under the above name. In 

 one specimen very faint and extremely fine longitudinal lines are 

 observable under a strong magnifier. 



