THE CYCOLOPHORID LAND M0LLUSJK9 OF AMERICA 115 



depression in its upper part. Umbilicus, greatest breadth 0.17 [4.25 

 mm.], least breadth 0.16 [4.0 nmi.]. Umbilical keel, almost obsolete. 

 Operculum, character of G. corrugatus, more concave than preceding ; 

 spiral lamina, about 8 whorls, upper margin scarcely reflected. 

 Height 0.58 [14.5 mm.], greatest breadth 0.64 [16.0 mm.], least breadth 

 0.56 [14.0 mm.]." 



This may be a small subglobular race of P. lineata (Gray), 

 occupying a range to the northeast of the typical form. 



POTERIA (PGTERIA) INUTILIS (Chitty) 



1857. Cyclotus inutilis Chitty, Proc. Zool. Soc. London, vol. 25, p. 155. 

 1898. Neocyclotus (Plectocyclotus) inutilis Kobelt and Mollendokff, Nachrb. 

 deutschen malak. Ges., vol. 29, p. 138, reprint. 



As I have not seen specimens referable to this species, I quote 

 Chitty's description : 



"/^orm, much depressed-conic. Colour, light brown; apex red- 

 brown. Sculpture, fine lines of growth on the 3i/4 whorls, thence 

 (for its size) roughly corrugated, except the last quarter of last 

 whorl, where, above, lines of growth are strong, with slight pitting; 

 lines of growth fine within the umbilicus. Spire, much depressed, 

 with convex outlines. Whorls, 4, well rounded, with very deep 

 suture. Aperture, oblique from left to right below, dilated above 

 and much expanded to the right, horizontally elliptical, 0.22 [5.5 

 mm.], 0.2 [5.0 mm.] vertically. Peritreme, rather sinuate above, 

 and detached from the penult whorl. Umhilicus, open and large, 

 greatest breadth 0.14 [3.5 mm.]. Umbilical keel, well defined inside 

 umbilicus. Operculuin, of G . J wmaicensis type, concave exteriorly, 

 with lamella of 5 whorls, like G. crassus. Height 0.31 [7.75 mm.], 

 greatest breadth 0.46 [11.5 mm.], least breadth 0.35 [8.75 mm.]" 



This species seems to be allied to P. lineata, but because of its 

 minute size it cannot be that species unless it should prove to be a 

 dwarf of that form. 



Cyclobakeria, new subgenus 



Poterias in which the spaces separating the turns of the lamella are 

 not reenforced by raised threads. 



Type: Gyclotus novae-spei Chitty=/*o^eWa (Cyclobakeria) novae- 

 spei (Chitty). 



The distribution of this subgenus is peculiar, being confined to the 

 two ends of the Island of Jamaica. Slight differences in the oper- 

 culum of the species from the two regions may indicate that further 

 division of this subgenus may be necessary. I am leaving the deter- 

 mination of this to the anatomists who may study the group. 



