145 



the upper margin, more or less dilated and reflected, so as to lie 

 more or less parallel to the plane of the operculum, but not so much 

 as to touch each consecutive whorl. Plane of operculum plain." 



FoRM § II. that of C. varians, Ad. 

 Operculum with outward-spreading whorls raised from its plane, 

 the upper margins of which are thickened and infiected, and reflected, 

 so as to meet and touch each consecutive whorl ; and form a corru- 

 gated, almost entire, planular surface; and when broken in half, 

 forming on either side something hke a number of italic capitals, 

 T^ T y, or the rails of a railvvay. "Where concave ou the outer 

 surface, the concavity is formed by the increasing height of the 

 lamina, the under side (as far as I have seen) being always planular. 



Form § III. thatofC seminudus, Ad. 

 Operculum with slightly elevated, bluntly thickened, and broadly 

 expanding whorls, the edges of which are wholly appressed to, and 

 not separated from the plane. 



Form § IV. that of C. Jamaicensis, Chemn. 

 Operculum with moderately raised narrow lamellar whorls, which 

 are flattened and blunt at the margin, and very slightly and narrowly 

 expanded and reflected outwards ; the plane of the operculum always 

 excentrically and sharply striated by lesser raised laminas. 



Form § V. that of C. Rupis-Fontis, Chitty. 

 Operculum with well-raised whorls, which are sharpened at the 

 margin, and stand almost vertical with the plane, the margin being 

 neither reflected nor inflected. 



Form § VI. that of C. jugosus, Ad. 

 Operculum with highly raised whorls, the margins of which are 

 sharp, and more or less inflected, convex interiorly and concave ex- 

 teriorly. 



These differences are broad enough whereon to found sub-subge- 

 nera, but from that I abstain. 



Under Form § I. I place my C. corrugatus and var. a, C. Port- 

 landemis, C. notatior, and var. a, C. notatus, C. Novce-Spei, C. cy- 

 cloatus, C. dubiosus, and C. suturalis. 



Under Form § II. C. varians and var. a, C. suhrugosus, C. cor- 

 rugatior, and var. magna, C. gemma, and C. zigsag. 



Under Form § III. C. seminudus, C. Be Burghcsanus, C. rudis- 

 planusęjve, C. pretiosus, C. Bairdianus, C. ruber, and C. asperulus. 



Under Form § IV. C. Jatnaicensis, C. Novus-Saltus, C. dentistig- 

 matus, C. crassus, and C. inutilis. 



Under Form § V. C. Rupis-Fontis, and C. corrugatissimus. 



Under Form § VI. ^C. jugosus, and vars. rufilabris, parvus and 

 striosus, C. pallescens, C. Westmorlandensis, C. nodosus, and C. 

 Besivieki. 



N. B. Of C perpallidus, the operculum is still imknowii. 

 No. CCCXXXVI. — Proceedings of the Zoological Societv. 



