206 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



It differs from Chondropoma (Chondropoma) mariguanicolum stoli- 

 dum in being more inflated and in having coarser spiral sculpture, which 

 is particularly the case on the base. 



The type (U.S.N.M. No. 469130) has 4.2 whorls remaining and 

 measures : Length, 14.2 mm. ; greater diameter, 8.8 mm. ; lesser diame- 

 ter, 7.0 mm. I collected this at Abraham Hill. 



The largest specimen (U.S.N.M. No. 391032), from the same locaHty, 

 has 4.2 whorls remaining and measures: Length, 19.2 mm.; greater 

 diameter, 11.8 mm.; lesser diameter, 9.8 mm, 



U.S.N.M. No. 391626 contains 139 topotypes from the same source. 



U.S.N.M. No. 391770 contains 13 specimens collected by Bartsch on 

 John Dean's place on the west side of Mariguana Island. 



U.S.N.M. No. 391620 contains 48 specimens collected by Bartsch from 

 Betsy Bay, Mariguana Island. 



In contrast I may mention the smallest specimen from John Dean's 

 place on the west side of Caicos, which has 4.0 whorls remaining and 

 measures: Length, 8.7 mm.; greater diameter, 6.8 mm.; lesser diame- 

 ter, 5.2 mm. 



I repeat, gradiants in size of this species may be found in any locality. 



CHONDROPOMA (CHONDROPOMA) MARIGUANICOLUM STOLIDUM, new subspecies 



Plate 34, Figure 8 



I collected this race on Booby Cay east of Mariguana Island. It is 

 characterized by having the whorls more rotund and the sculpture much 

 less strongly developed. 



The type (U.S.N.M. No. 469131) has 4.0 whorls remaining, and 

 measures: Length, 14.2 mm.; greater diameter, S.9 mm.; lesser diameter, 

 7.0 mm. 



U.S.N.M, No. 390453 contains 2 topotypes from the same source. 



CHONDROPOMA (CHONDROPOMA) PANNOSUM, new species 



Shell of medium size, elongate-ovate, with the sides rather straight, 

 white or pale horn-color. Nuclear whorls 2, well rounded, finely granu- 

 lose, forming a somewhat flattened apex; the last portion of the last 

 turn is marked by fine, hairlike, retractive threads, which grow stronger 

 on the first half postnuclear turn and finally pass into the regular post- 

 nuclear sculpture. The postnuclear whorls are almost flattened and are 

 marked by slender, retractively curved axial riblets, which form minute 

 nodules at the summit, and by spiral threads, which are a little stronger 

 than the axial riblets. Suture slightly channeled, most so on the last part 

 of the last turn. Periphery inflated, strongly rounded. Base short, in- 

 flated, strongly rounded, and marked by the continuation of the axial 

 riblets and spiral threads, which become increasingly more distantly 

 spaced from the periphery toward the umbilicus, and also extend over 

 the parietal wall. The last whorl is solute for a fraction of a turn. The 

 aperture is broadly ovate, decidedly angulated at the posterior angle, but 



