110 



§ 2. Peritreme more or less reflected. 



57. C. BiLABi atum. (pi. xxv. f. 81,82.) nob. Pterocyclos 

 bilabiatus, Benson. 



T. discoidea, spira depressa, fere plana, colore pallido, 

 castaneo-undulata; anfractibus 5, rotundatis, gradatim 

 majoribus, laevibus ; sutura distincta, profundiuscula ; aper- 

 tura fere circulari; peritremate duplici, interno simplici, 

 superne emarginato, externo extus undulato, sinuoso, superne 

 in tuberculum fornicatum desinente ; umbilico patulo, an- 

 fractibus distinctis; operculo circulari, spirali, intus concavo, 

 extus convexo, lamelloso. 



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

 colour, undulated with chestnut ; volutions five, rounded, in- 

 creasing gradually in size, quite smooth ; suture distinct, 

 rather deep ; aperture nearly circular, with a double peri- 

 treme ; inner peritreme simple, notched at the upper part, 

 outer one sinuous and undulated, running into a vaulted 

 tubercle at the upper part ; umbilicus large and spreading, 

 volutions distinct within ; operculum circular, spiral, concave 

 within, convex and lamellar externally. 



Brought from Salem, near Madras, by J. M. Heath, Esq. 



58. C. planorbulum. (pi. xxv. f. S3 to 86.) Lam. Anim. 

 sans. vert. vi. 2. p. 143. 



T. discoidea, spira depressa, plana, colore pallido, castaneo- 

 variegata; anfractibus 5, rotundatis, gradatim majoribus, 

 laevibus ; sutura distincta, profundiuscula ; apertura fere cir- 

 culari, peritremate incrassato, superne et extus reflexo, 

 ultimum versus anfractum desinente, fornicato ; umbilico 

 patulo. 



Shell discoid, spire depressed, flat, colour pale, varied with 

 chestnut ; volutions five, rounded, increasing very gradually 

 in size, smooth,with faintly marked transverse lines of growth ; 

 suture distinct, rather deep ; aperture nearly circular, with a 

 thickened peritreme, the upper and outer part of which is 

 reflected, and forms a vaulted projection running upon the 

 last volution ; umbilicus wide, spreading, the volutions con- 

 spicuous within. 



Several varieties were brought by Mr. Cuming from the 

 Philippine Islands : it is also found in Bengal. 



59. C. spiraculum. (pi. xxxi. f. 270. 271. 272. var. f. 

 273.) nob. Genus Spiraculum nonnull. 



T. suborbiculari, planorbula, crassiuscula, albicante, casta- 

 neo radiatim irregulariter strigata, epidermide fuscescente 



