91 



DESCRIPTIONS. 



§1 Peritreme not reflected. 



1 C. suTURALE. pi. xxiii, f. 1.2) tiob. 



T. orbiculato-depressa, tenui, epidermide olivacea indutd, 

 anfractibus 3-4, rotundatis, transversini tenuissime striatis, 

 sutura canaliculata ; linea levata, filiformi prope suturam ; 

 apertura circular!, superne emarginatione obsoleta ; peritre- 

 niate tenui, margine acutiusculo ; umbilico patulo ; operculo 

 concinne spirali. 



Shell of a depressed orbicular form, with a nearly flat 

 spire, thin and white, covered with a thin olive -coloured 

 epidermis ; whorls 3 to 4, rounded, finely striated trans- 

 versely, or in the direction of the axis ; suture canaliculated, 

 with an elevated, thread-like line next to it ; aperture cir- 

 cular, slightly notched at the upper edge, peritreme thin, 

 with a sharpish edge ; umbilicus wide, spreading ; operculum 

 thickish, testaceous, with a very fine spiral line on the outer 

 side. Demerara, Mr. Bainbridge. 



2. C. ASPERULUM (pi. xxiii, f. 3.) nob. 



T. orbiculato-subdepressa, tenui, translucida ; anfractibus 

 4 — 5, rotundatis, rugulosis ; sutura distincta ; apertura 

 ro tun data, superne acuminatiuscula, peritremate tenui, mar- 

 gine acutiusculo ; umbilico magno. 



Shell of a somewhat depressed nearly orbicular form, 

 thin, semitransparent, white ; volutions 4 — 5, minutely rugu- 

 lose all over ; suture distinct, aperture nearly circular, 

 but acuminated at the upper part where the peritreme is 

 joined to the last volution, peritreme not thickened, margin 

 sharp ; umbilicus large. Several specimens of this species 

 were in Mr. G. Humphrey's collection, labelled " Pyxis, 

 Jamaica." A young shell has a shelly operculum, and a 

 thick green epidermis. 



3. C. SEMiSTRiATUM. (pi. xxiii. f. 6) nob. 



T. orbiculato-subdepressa, tenui, albida, fasciis pallide 

 fuscis interruptis ; spira subprominula, apice olitvisiusculo ; 

 anfractibus 4 — 5, rotundatis, superne longitudinaliter striatis, 

 infra Irevibus ; sutura distincta ; apertura circulari, superne 

 subacuminata ; peritremate obsoletissime subreftexo, tenui, 

 margine acutiusculo ; umbilico magno ; operculo sulco externo 

 spirali, anfractibus 4 — 5. 



Shell of a somewhat depressed orbicular form ; thin, 

 whitish, with narrow pale brown interrupted bands; spire 



