HISPANIOLAN AND BAHAMAN ANNULARDDAE 217 



of Opisthosolen, I now select as type for that name Ctenopoma haham- 

 ense Shuttleworth = O/'w/Ao^o/^n biformis bahamensis (Shuttleworth) 

 Dall =Opisthosiphon (Opistho siphon) bahamensis (Shuttleworth). 



KEY TO THE BAHAMAN SUBGENERA OF OPISTHOSIPHON 



Spiral sculpture present. 



Spiral sculpture confined to umbilical wall Opisthosiphona 



Spiral sculpture not confined to umbilical wall Opisthosiphon 



Spiral sculpture absent Leptopisthosiphon 



Subgenus Opisthosiphona Henderson and Bartsch 



1920. Opisthosiphona Henderson and Bartsch, Proc. U. S. Nat. Mus., vol. 58, 

 p. 68. 



Opisthosiphons without spiral sculpture on spire and base, the spiral 

 threads being present in the umbilicus only, and with the axial ribs ter- 

 minating individually without fusing at the summit. There are no micro- 

 scopic axial lines between the axial ribs. 



Type species : Cyclostoma moreletianum Petit = Opisthosiphon (Opis- 

 thosiphona) moreletianum (Petit). 



KEY TO THE BAHAMAN SPECIES OF OPISTHOSIPHONA 



Outer lip of outer peristome broadly expanded. 

 Axial ribs distantly spaced. 



Axial ribs lamellose insulae-f elis 



Axial ribs not lamellose maynardi 



Axial ribs not distantly spaced simpsoni 



Outer lip of outer peristome not broadly expanded acklinsensis 



OPISTHOSIPHON (OPISTHOSIPHONA) INSIJI,AE-FEL.I8 Clench 



Plate 34, Figure 5 



1938. Opisthosiphon bahamense insulae-felis Clench, Bull. Mus. Comp. Zool., 

 vol. 80, pp. 515, 516, pi. 2, figs. 1, 7. 



Decollated shell ovate, soiled white in the dead stage. Nuclear whorls 

 decollated. The postnuclear whorls are slightly shouldered at the sum- 

 mit, well rounded, and crossed by slightly retractively curved, lamellose 

 axial ribs, which develop into cusps at the summit. These ribs are dis- 

 tantly spaced, and between them there are fine hairlines which vary in 

 number. Suture strongly constricted. Periphery well rounded. Base 

 short, well rounded, openly umbilicated, and marked by several spiral 

 threads which render the axial ribs nodulose. Aperture obliquely oval; 

 peristome double, the inner moderately exserted; the outer expanded 

 and reflected, a little narrower on the outer lip than on the inner and 

 parietal wall. The last whorl is slightly solute, but the expanded outer 

 peristome is adnate to the preceding turn. 



The specimen described and figured (Mus. Comp. Zool. No. 107906) 

 is a paratype. It was collected by Clench and Russell in 1936 on Cat 

 Island, Bahama. It has 3.4 whorls remaining and measures: Length, 

 10.9 mm.; greater diameter, 6.5 mm.; lesser diameter, 5.1 mm. 



The lamellose axial ribs will readily distinguish this species from all 

 the other known Opisthosiphonas, 



