118 



subeirculari, postice subacuminata, intus aurantiaca ; peristo- 

 mate albo, crasso, subreflexo, latere umbilicali incrassato, 

 lato, extenso, umbilicum majusculum plerumque claudente : 

 operculo elliptico, postice angulifero, anfractibus tribus, extus 

 striatis, intus leevibus. 



Shell subglobose, thick, whitish, sometimes light brownish 

 yellow, smooth, irregularly clathrated by elevated lines and 

 transverse strife ; spire short, obtuse, with 5 rounded volu- 

 tions, which are very finely spirally striated posteriorly and 

 delicately decussated, the last being very large and ventri- 

 cose ; suture distinct, but slender ; aperture nearly circular, 

 rather acuminated posteriorly, of an orange colour within and 

 with a white, thick, very slightly reflected peritreme, which 

 is thickened and expanded in the inner side, so as generally 

 to cover the rather large umbilicus ; operculum elliptical, 

 acuminated posteriorly, of three volutions, slightly convex 

 and striated externally, smooth and rather concave within. 



From the Island of Socotra. 



79. C. albicans, (pi. xxvi. f. 110, 111, 112.) nob. 



T. subglobosa, spira obtusa, anfractibus 5, rotundatis, 

 superne spiraliter sulcatis, infra lsevissimis, albicantibus ; 

 apertura subeirculari, superne subacuminata ; peritremate 

 incrassato, superne subsinuoso, infra externe crasso, reflexo ; 

 margine interno angulifero ; umbilico magno. 



Shell nearly globular, with an obtuse spire, consisting of 

 five rounded volutions, spirally grooved on the upper part, 

 very smooth below, and whitish ; aperture nearly circular, 

 rather acuminatad above, peritreme thickened, somewhat 

 sinuous above, the lower part of the outer edge thickened and 

 reflected, inner edge with an angle on the side of the umbili- 

 cus, which is large, and smooth within. 



80. C. calcareum. (pi. xxvi. f 1 13.) nob. C. sulcata, Lam. 

 T. globoso-conica, spira acuminata, alba: anfractibus 5, 



ventricosis, spiraliter sulcatis : sutura distincta : apertura 

 circulari, peritremate simplici, reflexo : umbilico mediocri, 

 intus spiraliter sulcato. 



Shell of a globoso-conical form, with an acuminated spire, 

 white, with five ventricose, spirally grooved volutions : suture 

 distinct : aperture circular : peritreme simple, reflected : um- 

 bilicus middle-sized, spirally grooved within. There is no 

 doubt of this being the C. sulcata of Lam. inasmuch as it 

 accords perfectly with his description, but it must not be 

 confounded with the C. sulcatum of Olivier. Lamarck speaks 

 of it as a very rare species. 



