mUOSTOMA — CycLOTDS. 129 



C. ravidns, Bens. Only in fiill-r^rown specimens the last whorl 

 at the aperture becomes detached from the previous whorl. The 

 operculum is first thin, flattened outside and slightly concave 

 inside; gradually the shape becomes convex outside, as the whorls 

 increase in number, and at the same time the internal concavity 

 enlarges." {StoJiczla.) 



The shell now figured is in the general collection of the British 

 Mus(Hnn, and measures: Major diam. 21"5, minor 18, alt. 12 mm. 



180. Rhiostoma strubelli, M'OUendorf. 



jRhiosfonia sfruhel/i, MuIlendorfF, Nachr. Deuts. Malak. Ges. xxxi, 

 1899, p. 1()(; ; Knbelt, Das Tiern^ich, I.ief. 1(3. 1902, p. 179; id., 

 Conch.-Cab., Oyclophoridae, ii, 1910, p. 759, pi. il'.i, tigs. 10, 11. 



Orujinal description : — " T. lateetaperte umbilicata, umbilico ^V 

 diametri ajquante, conoideo-depressa, solidiuscula, subtiliter sed 

 distincte striatnla, griseo-alba, strigis fulguratis castaneis picta, ad 

 peripheriam taeuia angusta fusca ornata. Spira breviter conoidea. 

 Anfr. 5 teretes, sutura sat profunde impressa submarginata dis- 

 iuncti, idtimus longe descendens, breviter solutus, in parte sohita 

 superne carinula obtusa,ad aperturam tubulo crassiusculo munitus. 

 Apert. fere diagonalis, circularis, peristoma breviter oxpansum, 

 sat incrassatum. Operculum subtestaceum breviter cylindriciim, 

 2 "5 mm. altnni. 



" Diam. IS, alt. 10 mm." {Mollendorff.) 



Huh. Burma : Kalow, Shan States {Strahell). 



Section CTCLOTE.^. 



Genus CYCLOTUS, Swainson. 



Ci/clofns, Swainson, Treat. Mulac. 1840, pp. 180, 330 (as subgenus 

 of Ct/clostoma) ; t'feiffer, Zeits. Malak. viii, 1851, p. 132 ; id.. Mod. 

 Pneum. 1852, p. 10 (as genus); Adams, Gen. Kec. Moll, ii, 

 1855, p. 274; Chenu, xMan.'Concliyl. i, pan 2, 1860, p. 485; Blau- 

 ford, A. M. N. H. ser. 3, xiii, 1804, p. 446 ; Pfeiffer, Men. Puemu. 

 Su))pl. 2, 1865, p. 14; Martens, Preiiss. Exped. Ost-Asien, Zool. 

 ii, 1807, p. 116; Nevill, Hand List, i, 1878, p. 255; Fischer, 

 Man. Concliyl. 1885, p. 745 (as subgenus of Pteroaucliis) ; 

 MiiUendorff, hev. Senckenb. iXat. Ges. 1890, p. 266 ; Ko'belt & 

 Mollendortf, Nachr. Deuts. !Malak. Ges. xxix, 1897, p. 110; id., 

 Cat. Pneum. 1899, p. 28; Sarasin, Land Moll. Celebes, 1899, 

 p. 35; Kobelt, Das Tierreicli, Lief. 10, 1902, p. 188; id., Conch, - 

 Cab., Cyclophoridae, ii, 1911, p. 773. 



Typk, C>/clotus varieyatus, Swainson. 



llanip'. Southern Asia, Southern China and Japan, New Guinea. 



Shell widely nmbilicated, flat or discoid, with a dark perio- 

 stracum ; peristome sim])le or provided with a wing. Operculum 

 composed of two lamina) separated by a deep furrow, the inner 

 membranaceous, the outer calcareous, flat, without process or 

 appendages. 



K 



