150 



at about one half of the lašt whorI, where the cornigation be- 

 comes coarse, irregular, and ill-defined, till little more than 

 coarse striae of growth are seen bebind the aperture. From the 

 periphery dowiiwards, the corrugations on the lašt whorl, for about 

 its first half, are much closer together than those above, and Ue 

 almost horizontally, but inclmiug from left above to right below ; 

 and, ontside the umbilical keel, the ręst of the whorl below the peri- 

 phery is much pitted. Striae of growth inside the umbilicus rather 

 fine. Sjnre much depressed, with convex outUnes. TVhorls nearly 

 5, well rounded with a deep suture. Aperture well rovmded, slightly 

 subaugular above. Peritreme rather reflected, and spread on the 

 right, sometimes double above ; thickened (as is usual) on the left, 

 and slightly detached from body-whorl. Umbilicus broad ; greatest 

 breadth, 0'3.5 ; least breadth, 0*31. umbilical keel well developed. 

 Operculum moderately concave above, planulate below, rather in- 

 clined to that of C. corrugatus form, from the cross lines on the 

 margin of the spirai lamina being less developed, but otherwise likę 

 the C. varians type in general character of closeness to one another. 

 8 or 9 lohorls, and still a vacuity in the centre. Height 0*7, greatest 

 breadth 0-98, least breadth, 0-84. 



Var. minor, Chitty, is much smaller ; being, height 0'53, greatest 

 breadth 0*8, least breadth 0'65. 



Var. magna, Chitty, is much more conical ; height 0"8, greatest 

 breadth 0-92, least breadth 0-81. 



C. GEMMA, Chitty. New Hope. 



Form, very much depressed-turbinate. Colour, bluish-white, with 

 a light brown epidermis. Sculpture, likę to C. corrugatior, but 

 corrugation commences almost at the first quarter of the 3rd 

 whorl ; corrugation very marked in proportion to size, as in 

 C. corrugatior ; sometimes in zigzag vertically, sometimes with dia- 

 gonal arrow-head-shaped indentations, the points being on the peri- 

 pherv, on the lašt whorl. Spire, much depressed, vvith convex 

 outlines. TVhorls, A\, well rounded with a deep suture, lašt vvhorl 

 much depressed. Aperture, widely expanded, especially on the 

 right side and below, slightly angular above. Peritreme, well ex- 

 panded on right side, more separated from body-whorl on left than 

 in C. corrugatior. Umbilicus, broad; greatest breadth, 0-21, least 

 breadth, 0-16. Umbilical keel, almost obsolete. Operculum, šame 

 as in C. corrugatior, with about 9 whorls. Height 0"41, greatest 

 breadth O -(i 6, least breadth 0-51. 



C. ZIGZAG, Chitty. Trelawny. 



Form, depressed-turbinate. Coloitr, white, with light brovvn epider- 

 mis. Sculpture, likę C. corrugatior in the upper whorls, only 

 very much finer and closer, and more regularly corrugated, in 

 zigzag form, on the lašt whorl, and finely corrugated all over 

 the under side, except behind the aperture, round the um- 

 bilicus. Sįure, moderately elevaled, vvith convex outlines. Whorls, 



