OCHRODERMA. 327 



pressed, white, with two weak, very oblique folds above and 

 conspicuously obliquely truncate below; parietal fold strong, 

 compressed, horizontally entering. Length 44, dam. 16, aper- 

 ture 17.5x9 mm. (Marts.). 



Caroline Is.: Ruk or Hogolu Island (0. Finsch). 



TornatelUna gigas MARTS., Sitzungsber. Ges. naturforsch- 

 ender Freunde in Berlin, Nov., 1880, p. 146 ; Conchol. Mitt- 

 heil., i, 91, pi. 17, f. 1-5. ANCEY, Le Naturaliste, iii, 1885, 

 p. 93; Journ. de Conchyl., 1903, p. 100. 



This splendid snail is remarkable for the solidity of the 

 shell, which is white under a cuticle of ochraceous or green- 

 ish-ochre color. The apical whorls to the number of about 

 3y 2 are faintly, delicately decussate. The growth-striae are 

 nearly straight and vertical at first, but on the last half- 

 whorl of the embryonic shell they become oblique, bending 

 forward below; there is then an oblique, forwardly-descend- 

 ing shallow groove and wrinkle at the end of 3y 2 whorls, 

 marking the limit of the nepionic stage. In the neanic stage 

 the faint growth-stria? become arcuate in the normal direc- 

 tion. The outer lip is thin and sharp but rapidly thickens in 

 the throat, where there seems to be the weak trace of a thicker 

 median callus. 



Section Ochrodermella n. sect. Shell small. Central tooth 

 larger than in Ochroderma, about one-third as wide as the 

 adjacent laterals. Marginal teeth with three subequal cusps. 

 Type 0. martensi. 



The three species of this Cocos Island group are closely 

 related, and further collections are needed to show whether 

 they are really separable specifically. 



2. 0. CUMINGIANA (Pfeiffer). PI. 47, fig. 20. 



Shell ovate-oblong, solid, striatulate, covered with an oliva- 

 ceous-buff cuticle. Spire long-conic, the apex acute. Whorls 

 5y 2 , slightly convex, the last about three-sevenths the total 

 length. Columella subarcuate, distinctly and obliquely trun- 

 cate. Parietal wall bearing a large, horizontally-entering 

 lamella. Aperture semioval, calloused within ; peristome sim- 

 ple, acute. Length 8, diam. 3.66, aperture 3.66 x 1.66 mm. 

 (P/r.). 



