NO. 1863. M0LLU8KS OF THE GENUS ALVANIA—BART8CH. 345 



reflected; parietal wall covered with a thick callus, which renders 

 the peritreme complete. 



Doctor Carpenter's specimens were taken from GTiaina and Spon- 

 dylus, at Mazatlan. The type, wliich has 6 post-nuclear whorls, and is 

 in the Liverpool Collection of the British Museum, measures : Length, 

 2.8 mm., diameter 0.95 mm. 



ALVANIA PROFUNDICOLA, new species. 

 Plate 30, fig. 5. 



Shell ovate, yellowish wliite, nucleus yellow. Nuclear whorls 3, 

 showing 8 fine spiral hrations, which are about half as wide as the 

 spaces that separate them. The spiral sulci between the lirations 

 are crossed by quite regular, very slender axial threads, lending the 

 surface of the nucleus a finely reticulated appearance. Post-nuclear 

 whorls well rounded, weakly shouldered at the summit, marked by 

 rather strong, very regular, curved axial ribs, of wliich 25 occur 

 upon the first, 26 upon the second, and 32 upon the penultimate 

 turn. Intercostal spaces about three times as \vide as the ribs, crossed 

 by fine spiral striations, of wliich the first below the summit is 

 stronger than the rest and passes over the ribs, constricting them so 

 as to form a series of crenulations at the suture. Anterior to this 

 line the spiral striations are usually much enfeebled. On the last 

 whorl there are about 12 of these fines between the periphery and the 

 summit. Suture strongly constricted. Periphery of the last whorl 

 well rounded. Base well rounded, decidedly attenuated anteriorly, 

 marked by the feeble continuations of the axial ribs, which become 

 evanescent on the middle of the base, and seven subequal and sub- 

 equally spaced spiral lirations. Aperture subcircular; posterior 

 angle obtuse; outer fip thin at the edge, reenforced immediately 

 belnnd the edge by a thick varix; inner Hp slender, decidedly curved, 

 and reflected over and appressed to the base; parietal wall covered 

 with a tlfick callus, which renders the peritreme complete. 



The type and 24 other specimens (Cat. No. 207606, U.S.N.M.) were 

 dredged by the United States Bureau of Fisheries steamer Albatross 

 at station 2808, in 634 fathoms, on coral sand bottom, bottom tem- 

 perature 39.9°, near the Galapagos Islands. The type has 4 post- 

 nuclear whorls, and measures: Length 3.2 mm., diameter L7 mm. 



ALVANIA HOODENSIS, new species. 

 Plate 30, fig. 3. 



Shell smaU, elongate-conic, white. Nuclear whorls a little more 

 than 1 , sufficiently eroded to make the question of sculpture doubtful. 

 Post-nuclear whorls slopingly shouldered at the summit, marked by 

 obsolete, rounded, rather broad, vertical axial ribs of which about 

 20 occur upon the second and 24 upon the third and the penultimate 



