HISPANIOLAN AND BAHAMAN ANNULARDDAE 191 



spaced, hairlike, retractively slanting axial threads. On the succeeding 

 turns the spiral sculpture makes its appearance and rapidly assumes the 

 dominant features of the sculpture. This consists of four or more strong 

 spiral keels, which are of more or less equal size and spacing. The fine, 

 closely approximated, hairlike axial riblets are best seen in the spaces 

 between the keels, and they are gathered in very conspicuous tufts at 

 the summit. Suture moderately constricted. Base short, well rounded, 

 narrowly umbilicated, and marked by the continuation of the axial 

 threads and four or five spiral cords equaling those on the spire. The 

 last whorl is solute for about one-fifth of a turn. Aperture oval, slightly 

 auriculate at the posterior angle. Peristome double. The outer moder- 

 ately expanded and reflected ; the inner adnate to the outer. Operculum 

 typically chondropsid. 



This species is found in the eastern Caicos group ranging from East 

 Caicos through South Caicos through Big Iguana Cay to Grand Caicos. 

 It breaks up into several subspecies which the key below will help to 

 differentiate. 



It differs from C. (C.) inagukolum in having more spiral keels. 



KEY TO THE SUBSPECIES OF CHONDROPOMA (CHONDROPS) BACONI 



Tufts at summit of whorls very strong. 



Whorls sHghtly inflated baconi 



Whorls not inflated rathbuni 



Tufts at summit of whorls not strong caicosense 



CHONDROPOMA (CHONDROPS) BACONI BACONI, new subspecies 



Plate 33, Figure 4 



Of this race I collected a large series on the hillside at the west end 

 of East Caicos on July 29, 1930. 



It differs from Chondropoma (Chondrops) baconi rathbuni in having 

 the whorls a little more inflated and in having the fine axial threads a 

 little finer, in which respect it resembles C. (C.) b. caicosense. 



The type (U.S.N. M. No. 469145) has a little more than 4 whorls 

 remaining and measures : Length, 10.8 mm. ; greater diameter, 5.4 mm. ; 

 lesser diameter, 4.9 mm. 



U.S.N.M. No. 391549 contains 62 topotypes from the same source. 



CHONDROPOMA (CHONDROPS) BACONI RATHBUNI, new subspecies 



Plate 33, Figure 9 



Of this shell I collected a large series on a hill facing the salt pond 

 on the west side of South Caicos. It resembles Chondropoma (Chon- 

 drops) baconi baconi in the strength of the nodulation at the summit 

 but has the axial threads a little stronger and the whorls less inflated. 



The type (U.S.N.M. No. 469146), which comes from the above 

 locality, has a little more than four whorls remaining and measures: 

 Length, 11.5 mm.; greater diameter, 5.8 mm.; lesser diameter, 5.0 mm. 



