HISPAMOLAN AND BAHAMAN ANNULARIIDAE 



243 



The type (U.S.N. M. No. 355428) was collected by the U.S. Bureau 

 of Fisheries on the shores of the Lagoon on Watling Island. This evi- 

 dently means the smaller of the two lagoons, which I have termed Lake 

 Ferdinand. The type has a little over 4 whorls and measures: Length, 

 9.8 mm. ; greater diameter, 4.8 mm. ; lesser diameter, 4.0 mm. 



Seventeen additional specimens out of a lot of 64 specimens (U.S.N.M. 

 No. 127480) yield the following average measurements: 



Genus COLONINA Bartsch 



1946. Colonina Bartsch, antea p. 97. 



Shell moderately large, ovate, with closely spaced axial riblets, which 

 are rendered vertebrated by the spiral sculpture. The axial ribs are gath- 

 ered into tufts at the summit and project above this as conspicuous den- 

 ticles. Aperture oval ; peristome double, the outer expanded on the inner 

 lip, slightly so on the outer, or this may be fused with the inner peristome 

 to form a sharp edge. The operculum bears a slightly raised lamella on 

 the inner edge of the whorls from which strongly elevated, retractively 

 slanting, slender lamellae radiate outwardly, fusing at their outer edge 

 into a solid ridge. The calcification of the operculum does not extend 

 to the outer edge of the chondroid basal plate but leaves a small space 

 showing between the turns. 



Type species: Colonina fortunensis, new species. 



KEY TO THE BAHAMAN SPECIES OF COLONINA 



Spiral sculpture consisting of strong cords or keels. 

 Outer peristome of outer lip expanded. 



Suture broadly channeled bryanti 



Suture not broadly channeled inaguella 



Outer peristome of outer lip not expanded. 



Shell large, length more than 15 mm fortunensis 



Shell small, length less than 12 mm nana 



Spiral sculpture consisting of feeble cords hydii 



COLONINA BRYANTI (Pfeiffer) 



Shell elongate-ovate, white. Nuclear whorls about 2, well rounded, 

 smooth. Postnuclear whorls inflated, rather strongly rounded, and marked 

 by strong spiral keels, of which six occur on all the whorls between 

 summit and suture. On the last whorl, however, intercalated cords may 

 make their appearance between the first and second and second and 

 third. In addition to the strong spiral cords, the whorls are marked by 

 very fine sublamellar axial riblets, which render the spiral keels ser- 



