10 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



rounded, slender riblets, which are separated by mere impressed lines. 

 These riblets either terminate individually in a toothlike element at the 

 summit or several of them become fused to form this structure. In ad- 

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

 threads of almost equal strength and spacing and separated by mere 

 impressed lines. The junctions of the axial riblets and these spiral 

 threads, which about equal the axial riblets in width, form small, low, 

 squarish tubercles, which lend to the entire surface a somewhat clothlike 

 texture. The suture is strongly constricted. Periphery of the last whorl 

 well rounded. The base is short, well rounded, rather openly umbilicated, 

 and marked by the continuation of the axial ribs and spiral threads, 

 which equal those on the spire and form a sculpture like that on the 

 spire. The umbilical wall is marked by eight slender spiral threads. The 

 last whorl is solute for about one-tenth of a turn and conspicuously 

 angulated at the posterior angle of the aperture. Aperture broadly oval, 

 slightly angulated at the posterior angle ; peristome simple, very slightly 

 expanded and scarcely at all reflected. The operculum is paucispiral with 

 almost subcentral nucleus, the outside covered with a thin deposit of 

 fine calcareous granules, which are absent at the margin. 



The specimen described and figured (U.S.N.M. No. 493317) is one 

 of two collected by Salle in the Dominican Republic. They are probably 

 topotypes and came from Azua. It has 6.4 whorls and measures : Length, 

 14.2 mm. ; greater diameter, 8.6 mm. ; lesser diameter, 6.3 mm. The other 

 specimen has a little more than 6 whorls and measures : Length, 14.6 mm. ; 

 greater diameter, 7.6 mm. ; lesser diameter, 6.5 mm. 



U.S.N.M. No. 493319 contains 2 specimens from the Redfield Collec- 

 tion labeled "Santo Domingo." 



CHONDBOPOMA (CHONDBOPOMORUS) HEMIOTUM (Pfeiffer) 



Plate 1, Figure 1 



1854. Cyclostoma (Chondropoma) hemiotum Pfeiffer, Proc. Zool. Soc. London, 



1852, p. 143. 

 1854. Cyclostoma hemiotum Pfeiffer, Martini-Chemnitz Conchylien Cabinet, ed. 



2, vol. 1, sect. 19, pp. 370-371, pi. 48, figs. 3, 4. 

 1920. Chondropoma (Chondropomorus) hemiotum Henderson and Bartsch, 



Proc. U. S. Nat. Mus., vol. 58, p. 61. 



Shell elongate-ovate, thin, semitransluscent, horn yellow, with a broad 

 faint pale brown subperipheral zone. Nuclear whorls decollated. The 

 postnuclear whorls are moderately rounded and marked by weak, retrac- 

 tively slanting, axial riblets, which are rather closely spaced and are 

 strengthened at the summit where usually several are gathered together 

 to form feeble denticles. In addition to the axial sculpture, the whorls 

 are marked by slender spiral threads, which are also weak, being about 

 as strong as the axial riblets, which they render very weakly nodulose. 

 The spaces enclosed between the axial ribs and the spiral threads are 



