26 Art. 1.— M. Yokoyama : 



This shell like the foregoing has its top truncate and the spire 

 hidden in a pit. The diameter increases towards below or front, 

 being smallest at about one-third the shell-height from the top 

 and greatest near the middle or a little above it. The surface where 

 the diameter is smallest appears slightly concave. The height of 

 the largest specimen is 3 millim. 



Fossil occurrence. — Otake and Shito (rare at both). Oji. 

 Lower Musashino of Miyata and Naganuma Zones. 



O. Volrtila angustafa^ (A. Adams), var. 



PI. I. Fig. 8. 



Volvula anijitstatd. Pilsbry, Catalogno, p. 8. Tryon, Manual Conch., XV, p. lJ4ii, pi. 



XXVI, fig, 67. 

 Bulla anijnstatn. A. Adams in SowerbyV: ïlies. Conch., II, p. 596, pi. CXXV, tig. 153. 



A few specimens. The shape agrees well with tlie above 

 mentioned species of Adams except the apex which is somewhat 

 blunter in our fossil. This difference, how^ever, can hardly be con- 

 sidered as more than a varietal one. The general shape of the shell 

 is cylindrical, tapering sliglitly towards behind. The aperture is 

 linear and much dilated in front. The outer lip is somewhat con- 

 tracted in the middle. 



Fossil occurrence. — Otake and Shito. 



Living. — Northern Japan. Philippines. New Guinea. 



lO. Volvula actif œf or »nis, Yokoyama. 

 PI. I. Fig. 9. 



Shell rather small, thin, fusiform, with apex ending in a blunt 

 spine. The greatest diameter is in the middle of the shell. Aper- 

 ture long, linear, dilated below and bordered on the inner side by 

 an elevated margin somewhat bent outward. Height twice the 

 diameter, or a trifle less. The largest specimen measures 5. 5 mil- 

 lim. in height. 



This species is quite like Volvula minuta Bush (Tryon, ^lan. 

 Conch., XV, p. 237, pi. XXII, fig. 20, pi. XXVI, fig. 57) which is 



