126 BULLETM 181, UNITE© STATES NlATIOlNlAiL MUSEUM 



wall is marked by strong, curved, rugose incremental ridges. Aper- 

 ture oblique, subcircular and angled at the posterior angle ; peristome 

 slightly thickened on the outer and basal lip and somewhat emarginu- 

 late on the parietal wall. Operculum typically cycladamsid. 



This species is nearest related to A. (C.) hairdianuni (Chitty), 

 from which it can be distinguished by the fact that the oblique 

 ridges on the last whorl cross the periphery undiminished. In 

 bairdianum they vanish on the base before reaching the periphery. 



I am recognizing two subspecies, which the following key and 

 descriptions will help to differentiate : 



KEY TO THE SUBSPECIES OF APEROSTOMA (CYCLADAMSIA) RUBER 



Shell large, greater diameter more than 21 mm ruber 



Shell smaller, greater diameter less than 18 mm pretiosum 



APEROSTOMA (CYCLADAMSIA) RUBER RUBER (Chitty) 



Plate 17, Figures 31-33 



1857. Cyclotus ruler Chitty, Proc. Zool. Soc. London, vol. 25, p. 153. 



This subspecies has the early whorls pale brown ; the part of the 

 periostracum remaining is chestnut-brown. In denuded specimens 

 the shell is flesh colored, with a pale brownish tinge and usually with 

 several broad bands of dark brown, the periphery appearing as a 

 lighter zone. 



This subspecies is distinguished from A. {C.) vniher pi^etioswrn 

 (Chitty) by its much larger size. 



Chitty cites Westmoreland as type locality. Westmoreland is the 

 westernmost as well as one of the largest parishes of Jamaica. An 

 absence of a definite locality makes it not unlikely that his shells 

 came from the St. Elizabeth Parish border. The specimen figured, 

 U.S.N.M. No. 535982, is from the C. B. Adams collection at Amherst 

 and bears the label C. semiriudum Adams var., St. Elizabeths Ja- 

 maica, E. Chitty donor ! This has 5 whorls and measures : Height, 

 15.3 mm. ; greater diameter, 22.0 mm. ; lesser diameter, 16.1 mm. 



It must be remembered that Adams visited Chitty and obtained 

 many specimens from him. Chitty did not venture to enter the de- 

 scriptive field until after Adams' death. We know that Chitty de- 

 scribed material from New Hope, Westmoreland, which is near the 

 southeastern border of Westmoreland. All the material that we 

 have seen with definite locality comes fi'om the region of Carisbrook, 

 St. Elizabeth. 



