CYCLOSTOMA. 
PuatTE XXIIT. 
Species 158. (Mus. Cuming.) 
CYCLOSTOMA FRAGILE. Cycl. testa subampliter perspective 
umbilicatd, acuminato-conicd, pellucido-alba, corned, 
anfractibus rotundatis, longitudinaliter irregulariter | 
plicato-striatis, ultimo sublavé convoluto; apertura 
circulari, labro simplici, superné subsinuato. 
THE FRAGILE CycLostoma. Shell rather largely per- 
spectively umbilicated, acuminately conical, trans- 
parent white, horny, whorls rounded, longitudinally 
irregularly plicately striated, last whorl rather loosely 
convoluted ; aperture circular, lip simple, slightly si- 
nuated at the upper part. 
Gunpiacu, MS. in Mus. Cuming. 
Hab, Cuba. 
A white transparent horny sharply convoluted shell, 
with the last whorl rather loose. 
Species 154. (Mus. Cuming.) 
CycLostoMa NivEUM. Cyel. testd latissimé aperté umbi- 
licatd, depressé discoided, sordidé albd, anfractibus 
angustis, lenté accrescentibus, spiraliter filoso-liratis, 
ultimo ad peripheriam carinato ; apertura pared, cir- 
culari, labro calloso, vix reflexo, marginibus disjunctis. 
THE snowy Cyctostoma. Shell very broadly openly 
umbilicated, depressly discoid, dead white, whorls 
narrow, increasing slowly, spirally thread-ridged, 
last whorl keeled at the periphery; aperture small, | 
circular, lip callous, scarcely reflected, margins dis- 
joined. 
Petit, Journ. Conch, 1850, p. 52. pl. 3. f. 7. 
Lithidion niveum, Pieitter. 
Hab. Madagascar. 
This is the first of five little species figured in this Plate, 
constituting Dr. Gray’s genus Lithidion. 
Species 155. (Mus. Cuming.) 
CycLostoma SovuLbyatianum, Cycl. testa late perspec- 
tivé wmbilicatd, depressd, subdiscoided, solida, fusco- 
carned, anfractibus angustis, spiraliter filoso-liratis, 
interstitiis concavis, subcrenulatis, sublus levibus, niten- 
tibus; apertura parva, peroblique semiovatd, fauce 
croced, labro calloso-reflexo, marginibus remote dis- 
junctis. 
SouLryeEr’s Cycnostoma. Shell broadly perspectively 
umbilicated, depressed, rather discoid, solid, brownish 
flesh-colour, whorls narrow, spirally thread-ridged, 
interstices concave, faintly crenulated, smooth and 
shining beneath; aperture small, very oblique, semi- 
ovate, interior saffron, lip callously reflected, margins 
widely disjoined. 
Perit, Journ. Conch. 1850, p. 52. pl. 3. f. 6. 
Cyclostoma paradoxum, Pfeiffer. 
Lithidion Souleyetianum, Pfeiffer. 
Hab. Island of Abd-el-Goury, near Socotra; Guillain. 
Not so depressly discoid as the preceding species, but 
having the aperture very oblique, with the margins un- 
usually widely separated. 
Species 156. (Mus. Cuming.) 
CYCLOSTOMA LITHIDION. Cycl. testd latissime excavato- 
umbilicatd, subdiscoided, solidiusculd, sordidé ulbd, an- 
Sractibus angustis, valide filoso-liratis, interstitiis con- 
cavo-suleatis ; apertura parva, perobliqua, labro cal- 
loso-reflewo, marginibus disjunctis. 
THE PEBBLE CycLostoma. Shell very broadly excavately 
umbilicated, nearly discoid, rather solid, dead white, 
whorls narrow, strongly thread-ribbed, interstices con- 
cavely grooved ; aperture small, very oblique, lip cal- 
lously reflected, margins disjoined. 
Sowerby, Thes. Conch. p. 111. pl. 31. f. 262. 
Lithidion sulcatum, Gray. 
Hab. Yemen, Arabia; Powis. 
Strongly thread-ridged throughout with a large regularly 
excavated perspective umbilicus. 
Species 157. (Mus. Cuming.) 
CycLostToMa DEPREsSSUM. Cycl. testd latissimé aperté 
umbilicatd, discoided, albidd, flammis et strigis pallidé 
corneis variegatd, spiré planulatd, suturd impressd, 
anfractibus angustis, lenté accrescentibus, supra spira- 
liter liratis et carinatis, infra levibus ; apertura parva, 
obliqud, labro subreflexo. 
THE DEPRESSED CycLostoma. Shell very broadly 
openly umbilicated, discoid, whitish, variegated with 
pale horny flames and streaks, spire rather flat, su- 
ture impressed, whorls narrow, slowly increasing, spi- 
April, 1862. 
