UROCOPTIS, S. G. COCHLODINELLA. 175 



the upper of the two cords in Idiostemma. There are fre- 

 quently some irregularly spaced ribs on the last whorl, as in 

 fig. 63. 



Subgenus COCHLODINELLA Pils. & Van., 1898. 



Proc..A. N. S. Phila. 1898, pp. 270, 274. Type U. poeyana. 



Shell similar to Urocoptis s. str. in general structure, but 

 small and thin, fusiform or subcylindric, the axis slender and 

 straight, arcuate in the last whorl only. Basal keel rather 

 weak or wanting. Spire truncate (rarely retained entire in 

 exceptional individuals) ; the rejected whorls numerous, at- 

 tenuate, apical whorls smooth, bulbous. 



Distribution, western Cuba, southern Florida. 



The dentition of the species of this group (pi. 61, fig. 19, 

 U. poeyana) closely resembles that of the smaller forms of 

 Gongylostoma (such as pi. 61, fig. 12, U. ivrighti). The rha- 

 chidian tooth is rather wide, its cusp equal to the ectocones 

 of the adjacent lateral teeth, and the number of teeth in a 

 transverse row is small, 10.1.10 in U. poeyana. The general 

 structure of the shell (aside from the axis), the large number 

 of deciduous whorls of the slender spire, and the smooth, 

 somewhat club-shaped earliest whorls, all show close relation- 

 ship to Gongylostoma, and indicate that Cochlodinella is a 

 branch of the same stock in which axial lamellae have either 

 never been developed, or have been wholly lost. I see at 

 present no way of determining whether the axis is primitive 

 or degenerate, but the former alternative is perhaps the sim- 

 pler. The group is not related to Jamaican species of similar 

 shell-structure, the testimony of the dentition showing the 

 resemblance of the shells to be adventitious. 



A group of Cuban species superficially similar to the U. 

 rosea group of Jamaica. The species gonostoma Gundl. and 

 paradoxa Arango, at one time referred to here, constitute the 

 new subgenus Lyobasis Pilsbry, in Opeas, the former species 

 being the type. This stenogyroid group is peculiar in the 

 detached and free latter half of the last whorl, the piriforra 

 aperture and continuous peristome. 



Urocoptis ftoridana (Cyl. floridana Dall, Trans. Wagner 



