290 CYCLOSTOMINiE. 



Genus CALLIA, Gray. 



Operculum thin, membranous, narrow-whorled. 



Shell pupiform, covered with a smooth, shining callus; 

 peristome sub- continuous, straight, scarcely thickened, 

 columellar margin entire above, appressed, reflexed, in the 

 young altogether closing the perforation. 



Ex. C. lubrica, Soicerby,]A. 80, fig. 8. Operculum, C. 

 lubrica, fig. 8, a, 8, h. 



A single species only is known, from the Philippine 

 Islands. 



Sub-fam. CYCLOSTOMIN.E. 



Operculum thick, solid, with a more or less thickened, 

 external, shelly coat, ovate, rarely sub-circular, composed 

 of a few gradually-increasing whorls ; nucleus somewhat ex- 

 centrical. 



Genus CYCLOSTOMUS, Montfort. 



Operculum shelly, few-whorled, whorls flat, the last broad ; 

 nucleus excentric. 



Shell globoso conical, or conical-turreted, thin, axis open, 

 simple; peristome simple or double, continuous, straight or 

 expanded. 



Syn. Cyclostoma, Lam. Ericia, Partiot. 



Ex. C. elegans, Mailer, pi. 86, fig. 9. Operculum, C. 

 elegans, fig. 9, a, 9, b. Shell, C. elegans, fig. 9, c. 



Algeria, the West Indies, the Canary Islands, and Europe, 

 harbour the majority of this genus, as restricted, one species, 

 C. elegans, forming the only representative of the family 

 Cyclophorithi' in the British Islands. The sub-genus Tro- 



