HISPANIOLAN AND BAHAMAN ANNULARIIDAE 247 



riphery inflated, strongly rounded. Base rather short, inflated, strongly 

 rounded and marked by eight spiral cords, which are a little less strong 

 than those on the spire. The umbilical wall is also marked by spiral 

 cords. Both of them are crossed by the continuation of the axial riblets. 

 The last whorl is sHghtly solute. Aperture broadly oval with a small 

 auricle at the posterior angle; peristome double, the outer quite broadly 

 expanded on the inner lip, narrowly so toward the parietal wall, the upper 

 portion of which is not expanded. On the outer lip the inner and outer 

 peristome becomes fused. On the inner lip and at the posterior angle, the 

 inner peristome is exserted and slightly reflected. Operculum typically 

 coloninid. 



The type (U.S.N.M. No. 536840) I collected on the east side of the 

 western Plana Island, Bahama Island. It has almost 4 whorls remain- 

 ing and measures: Length, 11.7 mm.; greater diameter, 7.4 mm.; lesser 

 diameter, 6.1 mm. 



U.S.N.M. No. 390888 contains 7 topotypes. 



Its small size will readily distinguish this species from Colonina fortun- 

 ensis. 



COLONINA HYDII (Weinland) 



Plate 38, Figures 1-3 



1862. Cyclostomus hydii Weinland, Malakazool. Blatter, vol. 9, p. 90. 



?1863. Chondroponm rude Reeve, Conchologia iconica, vol. 14, pi. 4, No. 28. 



1865. Cyclostoma hydii Pfeiffer, Monographia pneumonopomorum viventium, 



Suppl. 2, pp. 131-132. 

 1898. Colobostylus hydii Kobelt and Mollendorff, Nachr. deutschen malak. 



Ges., vol. 30, p. 192. 



Shell rather large, truncated, elongate-ovate, varying from soiled 

 white to pale brown. Nuclear whorls a little more than 2, well rounded, 

 smooth, forming a rather well elevated apex. The early postnuclear 

 whorls increase regularly in size, and if the shell were complete they 

 would give to this a broadly elongate-conic outline. The postnuclear 

 whorls are marked by low, rounded, spiral cords, of which 8 are present 

 on the first two turns, 10 on the third, and 12 on the last between the 

 summit and the periphery. The axial sculpture consists of slender, sub- 

 lamellar, rather closely spaced riblets, which render the spiral threads 

 weakly nodulose, the nodules being slightly elongate with their long axis 

 corresponding with the axial sculpture. These riblets show growth stages, 

 that is, a number of stronger are followed by weaker and more closely 

 spaced elements. At the summit of the whorls a number of these riblets 

 fuse to form rather irregular, conspicuous denticles. Of these axial rib- 

 lets, 261 occur on the last turn. Suture moderately constricted. Periphery 

 inflated, strongly rounded. Base moderately long, well rounded, and 

 marked by 11 spiral cords, which are as strong as those on the spire. 

 Four additional spiral cords of equal strength are apparent on the um- 



