NO. 1781. 



WEST AMERICAN M0LLU8KS—BARTSCH. 



155 



space between the sutures. Aperture rather large, very broadly 

 oval; posterior angle obtuse; outer lip thin, showing the external 

 sculpture within; columella oblique, somewhat curved and slightly 

 revolute ; parietal wall covered with a moderately thick callus. 



The above description is based on two specimens. One (Cat. No. 

 213367, U.S.N.M.) has furnished the nuclear characters, while another 

 (Cat. No. 4066, U.S.N.M.) has furnished the characters of the adult 

 whorls. The latter has lost the first two nuclear whorls, has eight 

 post-nuclear whorls, and measures: Length 6.8 mm., diameter 2.6 mm. 



Specimens examined. 



ALABA JEANNETT^, new species. 



Shell elongate-conic, semitransparent, with strong varices scattered 

 at irregular intervals. Nuclear whorls four, continuing the general 

 outline of the spire, well rounded, smooth except for very faint, 

 slender, axial threads which, in most instances, are 

 only apparent at the summit of the whorls. Post- 

 nuclear whorls well rounded, appressed at the sum- 

 mit ; the early ones smooth ; the later ones marked 

 by slender, incised, spiral lines, of which those on 

 the anterior half of the whorls between the sutures 

 and those on the posterior half of the base are 

 usually stronger than the rest. In addition to the 

 spiral sculpture, the whorls are marked at irregu- 

 lar intervals by strong, oblique varices. Suture 

 strongly constricted. Periphery of the 

 last whorl inflated, well rounded. Base 

 moderately long, well rounded, and in- 

 flated, its posterior half marked like the 

 anterior half between the sutures, bear- 

 ing the feeble extensions of the varices 

 large, broadly oval; posterior angle obtuse; outer hp thin 

 and transparent ; columella very oblique and somewhat 

 curved, slightly reflected over the reenforcing base ; parietal wall glazed 

 with a thin callus. 



The type (Cat. No. 182565, U.S.N.M.) has six post-nuclear whorls 

 and measures: Length 5 mm., diameter 2.1 mm. The present 

 species has been confounded with Alaba supralirata Carpenter. It 



Fig. 4.— Nu- 

 cleus OF 



ALABA JEAN- 

 NETTiE. 



Fig. 3.— Alaba jean- 



NETTiE. 



Aperture very 



