HISPANIOLAN AND BAHAMAN ANNULARIIDAE 



221 



has a little more than 3 whorls remaining, and measures: Length, 

 10. 1 mm.; greater diameter, 5.8 mm.; lesser diameter, 4.4 mm. 



Five topotypes (U.S.N.M. No. 180685) yield the following average 

 measurements : 



OPISTHOSIPHON (OPISTHOSIPHONA) ACKI.IN8KNSIS, new species 



Plate 36, Figure 9 



Shell rather large, horn-colored, with conspicuous interrupted spiral 

 bands of brown. The elements composing these bands are arranged in 

 both axial and spiral series. Nuclear whorls about 2, well rounded, 

 smooth. Postnuclear whorls well rounded, marked by moderately strong 

 axial riblets, some of which are expanded at the summit into rather con- 

 spicuous cusps. Of these riblets 139 occur on the last turn. Suture nar- 

 rowly channeled. Periphery well rounded. Base moderately long, well 

 rounded, openly umbilicated, and marked by the continuation of the 

 axial ribs, and on the outer portion of the umbilical wall by three mod- 

 erately strong spiral cords. The last whorl is solute for about one-tenth 

 of a turn. Aperture oval; peristome double, the outer broadly expanded 

 on the inner lip, narrowly expanded on the outer lip, forming a rather 

 conspicuous auricle at the posterior angle, which embraces the reflected 

 siphon; the inner peristome is slightly exserted and reflected. 



The type (U.S.N.M. No. 536801) I collected at Spring Point, Acklins 

 Island. It is a complete specimen, having 7.6 whorls and measuring: 

 Length, 15.0 mm.; greater diameter, 6.2 mm.; lesser diameter, 5.8 mm. 



U.S.N.M. No. 392355 contains 249 topotypes from the same source. 



U.S.N.M. No. 390873 contains 235 specimens collected by Bartsch 

 at Pinnacle Point. 



U.S.N.M. No. 390616 contains 47 specimens collected by Bartsch at 

 Indian Wells. 



U.S.N.M, No. 390917 contains i specimen collected by Bartsch at 

 Jamaica Bay. 



U.S.N.M. No. 391265 contains 35 specimens collected by Bartsch at 

 Delectable. 



U.S.N.M. No. 392220 contains 2 specimens collected by Bartsch at 

 Snug Corner. 



U.S.N.M. No. 390628 contains 5 specimens collected by Bartsch on 

 the hills in from Cornucopia, Acklins Island. 



