248 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



bilical wall. The base and umbilical wall also bear the continuation of 

 the axial riblets. The last whorl may be adnate or slightly solute. Even 

 when adnate there is a conspicuous portion of the outside of the parietal 

 wall that is reflected, and there is a very strong carina at the posterior 

 angle, marked by the denticulated riblets. Aperture oval with a moder- 

 ately large auricle at the posterior angle; peristome double, the outer 

 moderately broadly expanded on the inner lip, narrowly so on the pari- 

 etal wall, and fused with the inner peristome on the outer lip; the inner 

 peristome is reflected and appressed to the outer. Operculum typically 

 coloninid. 



The specimen described and figured (U.S.N.M. No. 425687) is one of 

 Weinland's original lot received from the Senckenburg Museum. It has 

 4.2 whorls remaining and measures: Length, 17.8 mm. ; greater diameter, 

 10.8 mm. ; lesser diameter, 9.3 mm. This specimen comes from Crooked 

 Island. The nuclear whorls were described from the Acklins Island speci- 

 mens. 



Another specimen (U.S.N.M. No. 394126) collected by me, comes 

 from French Wells, Crooked Island. 



I also collected a large series of specimens on Acklins Island, of which 

 Crooked Island forms almost a continuation. These agree with typical 

 C. hydii as far as sculpture is concerned. The hydii topotype, however, 

 has the last whorl adnate, while in almost all the specimens from Acklins 

 Island the last whorl is partly solute. If a larger series of specimens 

 from Crooked Island should prove that this is a constant character, it 

 will become desirable to bestow upon it a distinctive name. 



On Acklins Island I gathered the following specimens: 



U.S.N.M. No. 392372, 158 specimens from Spring Point. 



U.S.N.M. No. 392359, 47 specimens also from Spring Point. 



U.S.N.M. No. 392129, 6 specimens from Mason Bay, between Snug 

 Corner and Salt Lagoon. 



U.S.N.M. No. 391583, 17 specimens from the western shore of Salt 

 Lagoon. 



U.S.N.M. No. 391519, 5 specimens from Jamaica Bay. 



U.S.N.M. No. 390874, 53 specimens from Pinnacle Point. 



U.S.N.M. No. 392212, 4 specimens from Cornucopia. 



U.S.N.M. No. 394131, 16 specimens from Delectable. 



U.S.N.M. No. 393199, 2^ specimens from Indian Wells. 



U.S.N.M. No. 390912, 6 specimens from Jamaica Bay. 



U.S.N.M. No. 393338, 41 specimens from hills inland from Cornucopia. 



This species appears to be a sexually dimorphic form. While we have 

 not dissected specimens, I believe that the small individuals represent the 

 male. There are, however, intergrading individuals between the large 

 and small. I am also figuring a large and a small specimen from Acklins 

 Island. 



