NO. 186.*?. 



3IOLLU8KS OF THE GEXVS ALVAXIA—BARTSCH. 



359 



over the posterior fourth between the sutures, marked by strong, 

 shghtly retractive, axial ribs which are about one-fourth as wide 

 as the spaces that separate them. Of these ribs, 14 occur upon the 

 first, 16 upon the second, and 18 upon the penultimate turn. In 

 addition to the axial ribs, the whorls are marked between the sutures 

 by three strong, spiral cords which are almost as strong as the ribs 

 and divide the spaces between the sutures into four almost equal 

 portions. The intersections of the spiral cords and the axial ribs 

 form strong tubercles, while the spaces inclosed between them are 

 well impressed, rectangular pits, having their long axes parallel with 

 the spiral sculpture. Suture strongly constricted. Periphery of the 

 last whorl marked by a spiral sulcus equal to that wliich separates the 

 supraperipheral spiral cord from its posterior neighbor and, like it, 

 is crossed by the continuations of the axial ribs, wliich extend over 

 the first two basal spiral cords and render them tuberculate. Base 

 well rounded, rather short, produced anteriorly, marked by three 

 strong, sublamellar, spiral cords wliich are about one-tliird as wide 

 as the spaces that separate them. Aperture very oblique, twisted, 

 ovate; posterior angle obtuse; outer lip tliickened at the edge within 

 the lip, reenforced behind the edge by a strong varix, inner lip very 

 stout, strongly curved, and appressed to the base; parietal wall 

 covered with a very tliick callus, which renders the peritreme com- 

 plete. 



Professor Keep's cotypes were collected on mossy rocks at low tide 

 at San Diego, California. One of these, the specimen figured, is 

 Cat. No. 219564, U.S.N.M. This has 4 post-nuclear whorls and 

 measures: Length 3.2 mm., diameter 1.8 mm. 



Specimens examined. 



ALVANIA ALMO, new species. 

 Plate 32, fig. 1. 



Shell minute, broadly ovate, yellowish wdiite. Nuclear whorls one 

 and one-half, well rounded, smooth. Post-nuclear whorls somewhat 

 inflated, slopingly shouldered at the summit, marked by very slender, 

 almost vertical, axial ribs, of which 18 occur upon the first, and 20 



