194 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



CHONDBOPOMA (CHONDBOP8) BIFOBME COTTONENSE, new subspecies 



Plate 33, Figure 14 



Of this race I collected a large series of dead specimens on Cotton 

 Island between Grand Turk and Cay Sal. 



In this race we have a robust shell like that of Chondropoma (Chon- 

 drops) hiforme hiforme, but the spiral threads are less crowded than 

 in that subspecies and the axial threads are slightly inclined to be sub- 

 lamellar. The outer peristome is also more expanded. 



The type (U.S.N.M. No. 391506) has 4.3 whorls remaining and 

 measures : Length, 10.9 mm. ; greater diameter, 5.7 mm. ; lesser diame- 

 ter, 5.0 mm. 



U.S.N.M. No. 130830 contains 49 topotypes from the same source. 



CHONDBOPOMA (CHONDBOPS) BIFOBME ABENABIUM, new subspecies 



Plate 33, Figure 13 



This race, which is the largest and most robust of the group, I col- 

 lected on the south end of Sand Cay, Turk Island Group, August 2, 1930. 

 It has the whorls quite strongly inflated; suture deeply impressed, and 

 the axial sculpture is rather coarse. It resembles most closely Chondro- 

 poma (Chondrops) biforme cottonense, but is more robust and coarser 

 in every way than that subspecies. 



The type (U.S.N.M. No. 391864) has 4.3 whorls remaining and meas- 

 ures: Length, 11. 8 mm.; greater diameter, 6.0 mm.; lesser diameter, 

 5.3 mm. 



U.S.N.M. No. 392367 contains 3 topotypes from the same source. 



CHONDBOPOMA (CHONDBOPS) BIFOBME BEI.I.ENSE, new subspecies 



Plate 33, Figure 15 



This race I collected in numbers on Bell Cay, off Cape Comete, East 

 Caicos, July 27, 1930. It is a moderately thin elegant shell, with very 

 fine, closely spaced axial riblets and five spiral threads. It is most nearly 

 related to Chondropoma (Chondrops) biforme gambelense, from which 

 it is easily distinguished by its much finer axial sculpture. 



The type (U.S.N.M. No. 391559) has 4.8 whorls remaining, and 

 measures: Length, 12.5 mm.; greater diameter, 5.8 mm.; lesser diame- 

 ter, 4.9 mm. 



U.S.N.M. No. 391297 contains 92 topotypes from the same source. 



CHONDBOPOMA (CHONDBOPS) BIFOBME GAMBEI<ENSB, new subspecies 



Plate 33, Figure 12 



This race I collected in moderate numbers on Gambel's Cay, eastern 

 Grand Caicos, July 26, 1930. In shape it closely resembles Chondropoma 

 (Chondrops) biforme bellense, from which it is, however, easily distin- 

 guished by its much heavier axial sculpture, which is almost sublamellar. 



