250 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



on the umbilical wall. Last whorl solute for about one-fifth of a turn. 

 Aperture broadly oval; peristome double, the outer broadly expanded, 

 forming a rather conspicuous auricle at the posterior angle, of about the 

 same width except on the parietal wall, where it is much narrower. The 

 outer peristome is marked by concentric laminae, which are best shown 

 on the auricle. The inner peristome is rather strongly exserted and 

 slightly reflected. The operculum is typically colonellid. 



I am recognizing two subspecies, which the following key will help 

 to differentiate : 



KEY TO THE SUBSPECIES OF COLONELLA MARIGUANENSIS 



Axial ribs of the early whorls rather distantly spaced mariguanensis 



Axial ribs of the early whorls rather closely spaced planaensis 



COLONELLA MARIGUAJfENSIS aiABIGUANENSIS (Clench) 



Plate 38, Figure 4 



1937. Chondropoma mariguanense Clench, Proc. New England Zool. Club, vol. 

 16, p. 66, pi. 3, fig. 2. 



This subspecies I collected in very large numbers on Abraham Hill, 

 Mariguana Island, Bahama, and also in Betsy Bay and at John Dean's 

 place on the same island. 



The specimen figured (U.S.N.M. No. 536841) is one received from 

 Mr. Clench's type lot also collected at Abraham Hill. It has 4.4 whorls 

 remaining and measures: Length, 7.0 mm.; greater diameter, 3.1 mm. 



U.S.N.M. No. 391026 contains 1,448 topotypes from the same source. 



U.S.N.M. No. 391622 contains 89 specimens collected by Bartsch at 

 Betsy Bay, Mariguana Island. 



U.S.N.M. No. 391766 contains i specimen from John Dean's place, 

 west side of Mariguana Island, collected by Bartsch. 



This is very closely related to C. m. planaensis, but it can be differen- 

 tiated from that by having the denticles at the summit not quite as 

 strong, and in having the axial ribs of the early whorls much more dis- 

 tantly spaced. 



COLONELLA MARIGUANENSIS PLANAENSIS, new subspecies 



Plate 38, Figure 5 



This subspecies I collected in rather large numbers on the western 

 of the two Plana Islands, Bahama. It is closely related to Colonhw, 

 mariguanensis mariguanensis, but differs from it in having the axial rib- 

 lets at the summit much more pronounced, and in having the axial rib- 

 lets of the early whorls much more closely spaced. 



The type (U.S.N.M. No. 536842) comes from the east side of Plana 

 Island. It has 4.4 whorls remaining and measures : Length, 6.3 mm. ; 

 greater diameter, 2.9 mm. 



U.S.N.M. No. 390893 contains 1,586 topotypes from the same source. 



