106 BULLETIN 181, UNlTEiD StTATElS NArTTONlAiL MUSEUM 



actual type restriction for the genus, since Turho jamaicensis Chemnitz 

 (nonbinominal), rechristened orthodoxly Cyclostoma corrugatum in 

 1830 by Menke, is quite distinct from Turbo {Cyclostoma) jamaicensis 

 Gray. 



Therefore, I now further restrict the type designation by selecting 

 Turbo jamaicensis Gray {in Wood, Index testaceologicus, Suppl., p. 

 18, pi. 6, fig. 3, 1^'2%= Cyclostoma jamaicense, ibid., p. 36, same plate 

 and figure) as type. The synonymy is as follows : 



1850. Poteria Gray, Nomenclature of molluscous animals and shells in the col- 

 lection of the British Museum, pt. 1, Cyclophoridae, p. 11. (Type: Cyclostoma 

 jamaicensc Gray, in Wood.) 



1898. Plectocyclotus Kobeh^t and Moixendorff, Nachrb. deutschen malak. Ges.. 

 vol. 28, p. 139 (reprint; not in original). Type by subsequent designation 

 (Pilsbry, Proc. Acad. Nat. Sci. Philadelphia, p. 533) : Cyclostoma jamaicense 

 SoweThY= Poteria (Poteria) lineata (Gray). 



The group is characterized by the possession of a rather heavy 

 medium-sized shell, which has an umbilical bounding keel that varies 

 in different species from very strong to obsolete. The shell may be 

 strongly malleated or less so, or malleations may be absent. The oper- 

 culum bears a strongly elevated spiral lamella, which is almost at right 

 angles to the chondroid basal plate, and curves outward. The genus 

 is confined to Jamaica. 



I am recognizing two subgenera, which the following key will help 

 to differentiate : 



KEY TO THE SUBGENERA OF POTERIA 



Space between the opercular lamella with retractively curved raised 

 threads Poteria 



Space between the opercular lamella without retractively curved 

 raised threads Cyclobakeria 



Subgenus Poteria Gray 

 For synonymy see above. 



Poterias in which the broad spaces separating the turns of the la- 

 mella are reenforced with retractively curved raised threads. 



Type: Turbo {Cyclostoma) jamaicensis Gray = Poteria {Poteria) 

 jamaicensis (Gray). 



The radula of Poteria {Poteria) lineata (Gray) has the following 

 formula 3:3:3:3, and the jaw lacks distinct median projections. 

 The verge is situated on the back of the neck behind the tentacles. 

 It is swollen basally and provided with a seminal groove and a very 

 short simple appendage. 



