360 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.41. 



upon the penultimate turn. In addition to the axial sculpture, the 

 whorls are marked between the sutures by two spiral cords equaling 

 the ribs in strength. Of these, the first is a little posterior to the 

 middle of the whorls, bounding the sloping shoulder, while the second 

 is halfway between it and the suture. The intersections of the axial 

 ribs and spiral cords form slender tubercles, while the spaces inclosed 

 between them are well impressed, squarish pits. The spaces inclosed 

 between the first spiral cord and the summit and the axial ribs are 

 rhomboidal areas, having their long axes parallel to the axial sculp- 

 ture, while the spaces inclosed between the second spiral cord and 

 the axial ribs and the suture are squarish pits. Suture moderately 

 constricted. Periphery of the last whorl marked by a spiral sulcus, 

 which is crossed by the continuations of the axial ribs. Base nar- 

 rowly umbilicated — the umbilical chink being bounded by a tumid 

 area — moderately long, well rounded, slightly produced anteriorly, 

 marked on the posterior half by two spiral cords equaling those 

 between the sutures. Aperture almost circular; outer lip very thick 

 all around, reenforced by a strong varix; inner lip very stout, partly 

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

 a very thick callus which renders the peritreme complete. 



The type (Cat. No. 23749a, U.S.N.M.) comes from Santa Barbara 

 Island, California. It has three post-nuclear whorls and measures: 

 Length 1.5 mm., diameter 1 mm. 



ALVANIA OLDROYD.ffi:, new species. 

 Plate 32, fig. 3. 



Shell minute, broadly ovate, yellowish white. Nuclear whorls 

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

 weakly shouldered on the posterior fourth between the sutures, 

 marked by numerous slender rather closely spaced well rounded 

 slightly protractive axial ribs, of which 20 occur upon the first, 24 

 upon the second, and 28 upon the penultimate whorl. In addition 

 to the axial sculpture, the whorls are marked by slender spiral 

 threads which are almost equal to the axial ribs. Of these threads, 

 three occur upon the first and second whorl, dividing the space 

 between the sutures into four almost equal portions, the space at 

 the summit being a little wider than the rest; the first spiral thread 

 marks the termination of the sloping shoulder. On the penultimate 

 whorl an additional spiral cord makes its appearance in the space 

 immediately below the summit, a little nearer to the summit than the 

 first spiral cord on the previous whorl. The intersections of the 

 axial ribs and the spiral cords form slender rounded tubercles. 

 The spaces inclosed between the three cords on the early whorls 

 and the same on the last turn are squarish pits, wliile the spaces 

 between the summit and the first spiral cord and the axial ribs on 

 the first two turns are rectangular pits, having their long axes parallel 



