CYCLOSTOMIDiE. 285 



testaceous externally, flat, paucispiral ; the whorls obliquely sil- 

 lonated or striated, nucleus very excentric. 



LEONiA, Gray. Peristome simple, subreflected. Operculum 

 oval, calcareous, unispiral, convex cxternall}', nucleus lateral, 

 near the cokimellar lip. T. mamillaris^ Lam. (Ixxvi, 85). 

 Southern Europe. 



Cyclostoma, Lam. 



EtyTYi. — Cyclos^ circle, and stoma,, mouth. 



Distr. — 120 sp. About half in Madagascar, a few in the Bast 

 and West Indies, two or three in Europe. C. sulcatum, Lam. 

 (Ixxvi, 86). G. elegans, Miill. (Ixxvi, 87). 



Shell globular-conic or turriculated, thin, more or less widely 

 umbilicated ; aperture subcircular ; peristome single or double, 

 straight or slightly reflected. Operculum calcareous, paucispiral, 

 flattened, nucleus excentric. 



Animal with clavate tentacles ; sole of the foot divided by a 

 longitudinal groove, the sides moved alternately in walking; the 

 end of the long muzzle is also frequently applied, as by the 

 looping-snails (Truncatellse), and used to assist in climbing. 



TROPiDOPiiORA, Troschel. Shell depressed turbinate, widely 

 umbilicated or imperforate, with revolving carinse and stride; lip 

 reflected, sometimes covering a part of the umbilicus. A group 

 of usually large species inhabiting Madagascar. C. Cuvierianum, 

 Petit (Ixxvi, 88). 



LiTHiDiON, Gra3^ Shell depressed, widely umbilicated; aper- 

 ture subcircular ; peristome simple, thin or thickened. Operculum 

 paucispiral, with a strong subcentral carina. G. lithidion, Sowb. 

 (Ixxvi, 89). 



RBVOiLiA,Bourguignat,1881. (Dedicated toM. Georges Revoil.) 

 Shell depressed, discoidal, spirally ridged ; umbilicus wide in 

 young individuals, but entirely closed in adults by a thin dilation 

 of the columellar lip ; peristome continuous, dilated-reflexed, the 

 lip slightly ascending against the bod^^-whorl above. R. Milne- 

 Edioardsi, Bourg. E. Africa. Closely allied to Lithidion. 



OTOPOMA, Gray. Shell subglobose, umbilicated ; peristome 

 simple or a little reflected, with an ear-like process covering part 

 of the umbilicus. Operculum convex in the middle. 19 sp. 

 Socotra, Madagascar, Zanzibar, Mauritius, India. G. Naticoides, 

 Reel. (Ixxvi, 90). 



LiGATELLA, Martens. Shell rounded, turbinate-conical, usually 

 banded ; peritreme simple. Cape of Good Hope, Mauritius, 

 Madagascar. C. ligatum, Miill. (Ixxvi, 91). 



GEORGIA, Bourguignat, 1882. (Dedicated to Georges Revoil.) 

 Umbilical region entirely covered by a callous expansion of the 

 inner lip, which is not continuous with the labrum above. Oper- 

 culum perforated in the centre, interiorly concave, spiral, covei-ed 

 by a mucilaginous membrane, externally convex, four-whorled. 



