in 



induta ; anfractibus 5, rotundatis, nonnunquam leevibus, non- 

 nunquam spiraliter striatis, striis subasperis ; apertura circu- 

 lari, peritremate duplici, interno angusto, subreflexo, postice 

 emarginato, externo crassiusculo, reflexo, postice in canalem 

 desinente ; anfractu ultimo spiraculum tubulosum, vel fornica- 

 tum prope aperturam gerente ; umbilico maximo, expanso ; 

 operculo multispirali, intus concavo, extus convexo, lamina 

 spirali conspicua munito. 



Shell suborbicular, planorbular, thickish, whitish with irre- 

 gular chestnut coloured radiating streaks, covered with a 

 brown epidermis ; volutions 5, rounded, sometimes smooth, 

 sometimes with roughish spiral striee; aperture circular, peri- 

 treme double, inner narrow slightly reflected, notched poste- 

 riorly, outer thickish, broader, reflected and forming a canal 

 posteriorly ; the last volution with a tubular or vaulted spira- 

 cle near the aperture and close to the suture; umbilicus very 

 large and wide spreading; operculum of many volutions, 

 concave within, convex externally, and furnished with a white 

 prominent spiral lamina. From India, in Mr. Stainforth's 

 collection ; we have a smaller, pale coloured variety, also 

 from India. 



60. C. discoideum. (pi. xxv. f. 87, 88.) nob. 



T. discoidea, spira depressa, plana, pallida, epidermide 

 olivacea ; anfractibus 4 — 5, rotundatis, gradatim majoribus, 

 leevibus ; sutura distincta, profundiuscula ; apertura circulari, 

 peritremate superne et interne tenui, simplici, externe reflexo, 

 duplici ; umbilico patulo, anfractibus intus conspicuis. 



Shell discoid, with a depressed, nearly flat spire, of a pale 

 colour, with an olivaceous epidermis, volutions from four to 

 five, rounded, increasing very gradually in size, smooth ; 

 suture distinct, rather deep ; aperture circular, with the upper 

 and inner part of the peritreme thin and simple, the outer 

 part double and reflected ; umbilicus spreading, the volutions 

 distinct within. Demerara. 



61. C. lithidion. (pi. xxxi. f. 262.) nob. 



T. suborbiculari, subdepressa, crassa, albida, apice fusco ; 

 spira paululum levata, anfractibus 4£, rotundatis, spiraliter 

 sulcatis, prope suturam inconspicuam subplanulatis, antice 

 leevioribus ; apertura circulari, oblique posita, postice subangu- 

 lata, peritremate paululum reflexo; umbilicum versus declivi; 

 umbilico maximo, intus laevi. 



Shell nearly orbicular, rather flat, thick, whitish, with a 

 brown apex; spire slightly raised, of 4£ rounded, spirally 



