THE CYCLOPHOKID LAND MOLLUSKS OF AMEiRIC'A 129 



differing materially in the concavity of its outer surface, which ranges 

 from almost flat to decidedly concave. 



This species presents a difficult problem to the taxonomist, for I 

 was unable to find sharp, clearly cut geographic races, but I did 

 find intergrading elements in all the characters mentioned; that is, 

 elevation, width of umbilicus, intensity of sculpture or partial 

 absence thereof. 



I am recognizing four subspecies, which appear to have more or 

 less of a zoogeographic locus : 



KEY TO THE SUBSPECIES OF APEROSTOMA (CYCLADAMSIA) SEMINUDUM 



Periphery strongly sculptured. 



Spire helicoid scabratum 



Spire depressed-helicoid humile 



Periphery not strongly sculptured. 



Umbilicus narrow deburghaeanum 



Umbilicus not narrow seminudum 



APEROSTOMA (CYCLADAMSIA) SEMINUDUM SCABRATUM, new subspecies 

 Plate 18, Figures 26-28 



This subspecies has a well-elevated, helicoid outline and is exceed- 

 ingly roughly sculptured, the pitting extending over the periphery. 

 It is easily distinguished from A. (0.) s. humile, which also has the 

 pitting extending over the periphery, by its elevated form. 



The type, U.S.N.M. No. 535984, was collected by Dr. Welch at 

 The Alps, Trelawny Parish, Jamaica. It has 5 whorls and measures : 

 Height, 18.7 mm.; greater diameter, 26.0 mm.; lesser diameter, 

 19.3 mm. 



Welch also collected this race at Croydon, east-central Trelawny 

 Parish. Both of these localities represent the northeastern known 

 limit of the subspecies. 



APEROSTOMA (CYCLADAMSIA) SEMINUDUM HUMILE, new subspecies 



Plate 18, Figubbs 2&-31 



This subspecies has the shell decidedly depressed and finely roughly 

 sculptured, the pitting and wrinkling extending over the periphery. 

 It also has an exceedingly wide umbilicus. The depressed form and 

 large umbilicus and finer sculpture will distinguish this race from 

 A. (O.) seminudum scabratum. 



The type, U.S.N.M. No. 535985, has 5 whorls and measures : Height, 

 15.2 mm.; greater diameter, 25.6 mm.; lesser diameter, 19.0 mm. It 

 was collected by Dr. d'Alte Welch at Kyle, St. Elizabeth Parish, 

 Jamaica. 



