8 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 98 



neled anteriorly ; outer lip thick, marked at the edge by incremental 

 lines bearing 5 denticles within the edge in the expanded portion of 

 the aperture; inner lip appressed to the columella in its posterior half, 

 free on the anterior part. Parietal wall glazed with a thin callus except 

 near the outer lip where it develops into a low hump. 



The type, U.S.N.M. no. 472617, has a little more than 6 whorls 

 remaining and measures: Length, 8.1 mm.; greater diameter, 4.1 

 mm. ; lesser diameter, 3.4 mm. It was collected on Old Providence 

 Island. 



ALVANIA NIGRESCENS, n. sp. 



Plate 2, fig. 5 



Shell minute, elongate-ovate, dark chestnut brown, a little paler on 

 the outer and basal lip. Nuclear whorls about 2, well rounded, smooth. 

 Postnuclear whorls moderately rounded, marked by strong axial ribs 

 which are about as wide as the spaces that separate them and which 

 are rendered decidedly tuberculated by the 3 spiral cords at their 

 junction. There are 17 of these ribs on the last whorl. The spaces 

 enclosed between the axial ribs and spiral cords are rounded pits. 

 Suture strongly constricted. Periphery marked by a spinal cord a 

 little less strong than those of the spire, bearing feeble tubercles. Base 

 well rounded, slightly excavated at the columella and marked by 4 

 spiral cords, of which the first below the periphery is stronger than 

 the rest, which are of equal strength. In addition to this, the entire 

 base is marked by incremental lines. Aperture subcircular. Peristome 

 double ; the outer is present only on the outer and basal lip, thick and 

 marked by concentric striations ; the inner is slightly exserted. 



The type, U.S.N.M. no. 472621, has 5.5 whorls and measures: 

 Length, 3.1 mm. ; diameter, 1.5 mm. 



It was collected in a tide pool on Old Providence Island. 



PEASIELLA ROOSEVELTI, n. sp. 



Plate 2, figs. 1-3 



Shell small, broadly conic, with zigzag axial bands of blackish 

 brown, alternating with bluish white bands of the same width. These 

 bands terminate at the periphery in large alternating light and dark 

 spots. The base is marked by a broad band of alternating dark and 

 light spots adjoining the periphery and 2 similar bands on the keels ; 

 in the middle one, however, the light areas are feebly tinged with 

 brown. The columellar region is also pale brown. The interior of the 



