147 



whorl much depressed above, at, and behiud the aperture. Aperture, 

 rather obliąue in incomplete shells, subelliptical and subangular 

 above, likę a hanging pear — in finished shells, snbcircular, rather 

 dilated below on the right side, and the angularity above becoming 

 almost obsolete by the thickening of the outside. Peritreme, well 

 thickened and blunt all round. Umbilicus, deep and comparatively nar- 

 row ; greatest breadth, that is from side to side at the įimbilical keel*, 

 about 0'36, and least breadth 0*28. Umbilical keel, narrowly and 

 roundly pinched up, the strise of growth extending over it imbricatedly 

 from the hollow. Operculum, greatest breadth 0*5 1, least breadth0"46 

 — slightly concave externally, with about f 9 outward bending, 

 spirai whorls of laminse rising from its plane, the summits of which 

 spread, and are reflected outwards, but widely separated from one 

 another, nearly parallel to the plane, and striated eccentrically, as likę 

 water flying oflf a turned wheel by centrifugal force ; lamina well 

 detached above from the plane, and from each other whorl. Height 

 of shell, 1 inch; greatest breadth T 2, least breadth 1 inchĮ. 



C. CORRUGATUS, var. a (?), Chitty. 



This shell diifers from C. corrugatus in being much smaller. 

 Height O- 8, greatest breadth 0*94, least breadth O • 75 ; greatest breadth 

 of iimbilicus 0'27, least breadth 0*2 ; greatest breadth of operculum 

 0"43, least breadth 0"37. The corrugation is finer. It is sometimes 

 ąuasi smooth below, and marked with bands likę C. Jamaicensis with 

 transverse raised sub-obsolete lines. Umbilical keel is less promi- 

 nent. 



Whorls 5. Whorls of operculum about 6 or 7. 



C. PoRTLANDENSis, Chitty. Portland. 



Form, depressed-turbinate. Colour, blueish-white with a deep bistre 

 brown epidermis ; apex blood-red sometimes. Sculpture, 'S\ of 

 upper whorls coarse, strise of growth becoming thenceforth deeply 

 corrugated vertically on the upper part of the lašt whorl until about 

 the lašt third, vehere the corrugation ceases ; the strise of growth are 

 finer and a few pits occur, and a few transverse obsolete ridges 

 appear. No corrugation at the periphery : a few pits, and a slight 

 corrugation surround the outside of the umbilical keel. Umbilical 

 keel and strise of growth within the umbilicus are much stronger 

 thaii in C. corrugatus. Spire, and outlines likę C. corrugatus. 

 TFhorls, b\, lašt whorl and about ^th of penult whorl depressed 

 above, belovy^ the suture. Aperture, likę C. corrugatus, but rather 

 more expanded on right than on left side ; obliąue to axis, as C. cor- 

 rugatus. Peritreme, likę C. corrugatus. Umbilicus, much wider in 



* The measnrement of the umbilicus in all instances is taken from side to side 

 from the inner edge of the umbilical keel, taking care that the points of the com- 

 passes shall be at a right angle with the axis of the shell. 



t The nuclear centre and second whorl are probably never seen in mature shells, 

 froin their extreme delicacy while young, which cauies the appeavauce of being 

 devoid of laminae in the extreme centre. 



t All my measurements are in decimals of an inch. 



