98 



20. C. listeri. (pi. xxiii. f. 22. 23.) Gray. Mus. Brit. 

 T. subglobosa, crassiuscula, spira conoidea, subacumi- 

 nata, anfractibus 4 — 5, rotundatis, leevibus, nonnunquam 

 superne spiraliter obsolete striatis ; sutura distincta ; aper- 

 tura circulari, perltremate subincrassato, superne angulato, 

 latere umbilicali calloso, callo umbilicum partim obtegente ; 

 umbilico parvo, spiraliter striate 



Shell nearly globose, thickish, spire conoidal, rather acu- 

 minated ; volutions 4 — 5 rounded, smooth, sometimes 

 obsoletely striated longitudinally, more distinctly so in young 

 specimens ; suture distinct ; aperture circular ; peritreme 

 somewhat thickened, angular at the upper part, spread- 

 ing on the umbilical side into a callus which partly covers 

 the small spirally striated umbilicus. Mauritius. 



21. C. ligatum. (pi xxiii, f. 24.) Lam. Anim. sans Vert. 

 T. tenui, subglobosa, spira conoidea, subacuminata ; 



anfractibus 5 — 6, rotundatis, obsoletissime longitudinaliter 

 et transversim oblique striatis ; sutura distinta ; apertura 

 circulari, superne subangulata ; peritremate tenui, paululum 

 subreflexo, latere umbilicali patente; umbilico parvo, lsevissimo. 



Shell thin, subglobose, with a conoidal, rather acumi- 

 nated spire, consisting of 5 — 6 rounded volutions which 

 are very obsoletely striated longitudinally on the upper part, 

 these strife being obliquely crossed by other transverse striee 

 which are equally faint, the suture is strongly marked ; the 

 aperture is circular, rather angular at the upper part; 

 peritreme thin, very slightly reflected, spreading so as partly 

 to cover the umbilicus on the inner side ; umbilicus small, and 

 together with the lower part of the volutions quite smooth. 

 The apex is of a dark colour. 



22. C.AFFiNE.(pl.xxiii. f. 25. 26) nob. Turbo ligatus, Wood. 

 T. tenui, subglobosa, spira conoidea, subacuminata; apice 



obtuso ; anfractibus 4 — 5, rotundatis, leevigatis; apertura cir- 

 culari, superne subangulata ; peritremate tenui, latere umbili- 

 cali paululum reflexo ; umbilico parvo spiraliter sulcato ; oper- 

 culo lasvigato, nucleo sublaterali. 



Shell thin, nearly globose, with a conoidal, rather acu- 

 minated spire, whose apex is obtuse ; volutions 4 — 5, 

 rounded, smooth ; aperture circular, slightly angular at the 

 upper part ; peritreme thin, very slightly reflected on the 

 umbilical side ; umbilicus small, spirally grooved ; operculum 

 smooth, with a somewhat lateral nucleus. 



