260 BULLETIN 181, UNITED STATES NATIOINIAL MUSEUM 



the end evanescent. The summit of the last whorl drops slightly below 

 the periphery. Base openly umbilicated, inflated, well rounded, and 

 marked by the feeble continuation of the axial ribs, which almost 

 vanish on the umbilical wall. Aperture circular, with a slight angu- 

 lation at the posterior angle; peristome simple; outer lip very thin; 

 inner slightly thickened. The parietal wall is covered with a thin 

 callus which renders the peritreme complete. 



The type, U.S.N.M. No. 524126, comes from Balsas, Peru. It has 4 

 whorls and measures: Height, 13.8 mm.; greater diameter, 23.3 mm.; 

 lesser diameter, 16.4 mm. Height of aperture, 9.3 mm. ; diameter, 10.2 

 mm. A topotype has the U.S.N.M. No. 524127. 



This species resembles most nearly A. (A.) popayanum (Lea), from 

 which the feeble basal sculpture and stronger ribs on the upper surface 

 will readily distinguish it as well as the absence of strong scratching 

 on the last whorl. 



APEROSTOMA (APEROSTOMA) CARDOZI (H, B. Baker) 



Plate 39, Figures 4-6 



1923. Poteria (Neocyclotus) dunkeri cardozi H. B. Bakeb, Occ. Pap. Mus. Zool. 

 Univ. Michigan, No. 137, pp. 43, 44, pi. 5, fig. R. 



Shell small, depressed-helicoid, horn colored, with a broad brownish 

 band extending from the periphery over the anterior two-fifths of the 

 base. This band is bordered on each side by a narrow darker zone, and 

 there is an obsolete stripe of this darker coloration midway between 

 these two in the specimen figured. The basal portion is a little paler 

 than the upper surface ; interior of aperture bluish white. The nucleus 

 consists of 2 well-rounded, smooth turns. The postnuclear whorls are 

 somewhat inflated, well rounded, and marked by retractively curved, 

 moderately rough incremental lines, which develop into irregular 

 obsolete riblets on the last half turn. Suture strongly impressed. 

 Periphery obsoletely angulated. Base openly umbilicated, inflated, 

 well rounded and marked like the upper surface. Aperture circular ; 

 peristome simple, thin, sharp. The parietal wall is covered by a mod- 

 erately thick callus. Operculum typically aperostomid, showing 7 

 whorls. 



The specimen described and figured is one of two lent by Professor 

 Goodrich for examination. It comes from La Fria, Venezuela. It is 

 a topotype having 3.7 whorls and measures : Height, 8.9 mm. ; greater 

 diameter, 16.5 mm.; lesser diameter, 11.7 mm. Height of aperture, 

 7 mm. ; diameter, 7.3 mm. 



Baker's type has 3.7 whorls and measures : Height, 9.4 mm. ; greater 

 diameter, 17 mm. Height of aperture, 7.5 mm. ; diameter, 7.5 mm. 



This species appears most nearly related to A. {A.) halsasense but 

 can readily be differentiated from it by its much smaller size. 



