\o. 1863. MOLLUSKS OF THE GENUS ALVAXIA—BARTSCH. 355 



ribs. Base attenuated anteriorly, marked by five strong, spiral cords 

 which are almost equal. The spaces separating these cords are a little 

 narrower than the cords and are crossed by axial lines of growth. 

 Aperture very oblique, ovate; posterior angle obtuse; outer lip very 

 much thickened by an external varix; inner lip very stout, very 

 strongly curved, reflected over, and appressed to the base; pari- 

 etal wall covered with a thick callus wliich renders the perifreme 

 complete. 



The type has 4 post-nuclear whorls and measures: Length 2.4 mm., 

 diameter 1.1 mm. It and 16 other specimens (Cat. No. 195009, 

 U.S.N.M.) were dredged by the United States Bureau of Fisheries 

 steamer Albatross at station 2813 in 40 fathoms, on coral sand bottom, 

 bottom temperature 81°, off Galapagos Islands. 



ALVANIA IMA, new species. 

 Plate 32, fig. 8. 



Shell elongate-ovate, white excepting a broad, 3'ellow band which 

 encircles the periphery and shows above the suture on all the turns. 

 Nuclear whorls at least two, smooth. Post-nuclear whorls narrowly, 

 slopingly shouldered at the summit, marked by strong, protractive, 

 axial ribs, of which 14 occur upon the first, 18 upon the second, and 

 20 upon the penultimate turn. In addition to the axial ribs, the 

 whorls are marked between the sutures by three spiral cords, of which 

 the first — which is quite slender — is at the summit; the second, which 

 is very broad, being double the width of the next, is on the middle of 

 the whorl; while the third, which is a little stronger than the first, 

 forms the posterior border of the deeply channeled suture. The space 

 separating the first cord from the median one is about as wide as the 

 median cord, while that which separates the median from the third is 

 equal to the third cord. The intersections of the axial ribs and spiral 

 cords form tubercles which are small and rounded on the first cord; 

 on the second they are truncated posteriorly, sloping gently anteriorly, 

 somewhat flattened and enlarged; on the third they are somewhat 

 flattened, truncated posteriorly and gently rounded anteriorly. The 

 weak cord at the summit and the broad space immediately below it 

 give to the whorls a constricted appearance at this point. Periphery 

 of the last whorl marked by a deep sulcus across which the axial ribs 

 do not extend. Base well rounded, produced anteriorly, marked by 

 five spiral cords, which grow successively weaker from the periphery 

 to the columella. Aperture very oblique; posterior angle obtuse; 

 outer lip thin at the edge, reenforced immediately behind the edge by 

 a strong varix-; inner lip stout, strongly curved, and reflected over, 

 and appressed to the base. 



The type and two other specimens (Cat. No. 213697, U.S.N.M.) 

 were dredged by the United States Bureau of Fisheries steamer 



