306 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



slender interrupted spiral bands of brown. The peristome is of the 

 same color as the ground color of the shell except for the numerous 

 very decided rays present on both sides of the expanded portion. 



The type, U.S.N.M. no. 367881, has 5.5 whorls remaining and 

 measures: Length, 24.9 mm; greater diameter, 15.5 mm; lesser diam- 

 eter, 11.0 mm. 



CHONDROTHYRELLA, new genus 



Shell small, varying in shape from ovate to subglobular. Thei 

 shells may be unicolor or spirally banded. Nuclear whorls about 2, 

 well rounded, smooth except the last part of the last turn, which 

 shows the beginning of the postnuclear sculpture. Postnuclear 

 whorls more or less inflated, strongly rounded, latticed with slender 

 axial riblets and spiral threads, which may form cusps at their in- 

 tersections. Suture well impressed, simple. Periphery strongly 

 rounded. Base more or less inflated, strongly rounded, marked by 

 the continuations of the axial ribs and spiral tlireads. Umbilicus 

 open or closed. Aperture broadly oval to subcircular. Peristome 

 double, the inner little exserted, the outer expanded, cut or folded 

 on the inner lip and more or less reflected over the umbilicus ; parietal 

 wall covered with a strong callus. A breathing pore is present a 

 little within the edge of the aperture on the parietal wall near th© 

 posterior angle. This may open into the exterior at the posterior 

 angle where the whorls are solute or into the umbilicus by means of 

 a canal below the parietal callus: breathing may take place through 

 the umbilicus or when this is closed through the decollated apex. 

 Operculum simple, paucispiral, with more or less of a granular cal- 

 careous deposit. 



Type: Chondrothyrella {Chondrothyrella) pudica (Orbigny). 



This genus of small species is confined to the eastern part of Pinar 

 del Kio Province and the western and central parts of Habana 

 Province. 



KEY TO THE SUBGENERA OF GENUS CHONDROTHYRELLA 



Umbilicus open Plicathyrella 



Umbilicus closed Chondrothyrella 



Plicathyrella, new subgenus 



Chondrothyrella with the umbilicus open. Breathing pore open- 

 ing directly to the exterior where the last whorl is solute or through 

 a channel in the parietal callus, connecting with the umbilicus where 

 the last whorl is adnate to the preceding turn. Outer peristome of 

 the inner lip not cut but folded in the middle. 



Type: Chondrothyrella {Plicathyrella) assimilis (Gundlach) 

 Pfeiffer. 



