HISPANIOLAN AND BAHAMAN ANNULARIIDAE 219 



riphery of the last whorl well rounded. Base short, openly umbilicated, 

 strongly rounded. Within the umbilical area a number of spiral cords 

 are present. Aperture broadly oval, almost subcircular ; peristome double, 

 the outer expanded, marked by feeble concentric lamellae, adnate to the 

 preceding turn on the parietal wall; there is a feeble auricle at the 

 posterior angle which is appressed to the breathing siphon; the inner 

 peristome is slightly exserted and slightly reflected. Operculum typically 

 opisthosiphonid. 



This species is present on the northern Bahamas where it breaks up 

 into several subspecies as follows : 



KEY TO THE SUBSPECIES OP OPISTHOSIPHON (OPISTHOSIPHONA) SIMPSONI 



Axial ribs very closely spaced. 



Whorls conspicuously banded simpsoni 



Whorls not conspicuously banded bryanti 



Axial ribs not very closely spaced. 



Inner lip of outer peristome very broad abacoensis 



Inner lip of outer peristome moderately broad saccharinus 



OPISTHOSIPHON (OPISTHOSIPHONA) SIMPSONI SIMPSONI, new subspecies 



Plate 36, Figure 1 



This subspecies was collected by Owen Bryant at Riding Point, Grand 

 Bahama. 



In the closeness of the ribbing, this subspecies resembles most nearly 

 Opisthosiphon (Ofisthosiphona) simpsoni bryanti, from which it is 

 easily distinguished by its more cylindroid form, less open umbilicus, and 

 absence of conspicuous spiral banding. 



The type (U.S.N.M. No. 355449) has 102 axial ribs on the last whorl. 

 It has a little more than 4 whorls remaining and measures: Length, 

 ii.o mm.; greater diameter, 6.0 mm.; lesser diameter, 4.9 mm. 



U.S.N.M. No. 180682 contains 13 topotypes, which yield the follow- 

 ing additional average measurements : 



OPISTHOSIPHON (OPISTHOSIPHONA) SIMPSONI BRYANTI, new subspecies 



Plate 36, Figure 3 



This subspecies was collected by Owen Bryant at Lubbers Quarters, 

 a cay lying a little south of the center of the east coast of Abaco Island. 



This subspecies has the axial riblets closely spaced. In this character 

 it resembles Opisthosiphon (Opisthosiphona) simpsoni simpsoni, from 



