CYCLOSTOMA.—Puarr XXIII. 
rally ridged and keeled above, smooth below; aper- 
ture small, oblique, lip a little reflected. 
Sowerby, Thes. Conch. p. 161. pl. 31 B. f. 306, 307. 
Lithidion depressum, Pfeiffer. 
2 
Tab. 
More discoidly convoluted, and therefore more widely 
openly umbilicated than the preceding species. 
Species 158. (Mus. Cuming.) 
CYCLOSTOMA DESCISCENS. Cycl. testd profunde excavato- 
umbilicatd, subdiscoided, carneo-albidad, anfractibus 
angustis, supra spiraliter tenuiliratis, infra levibus, 
submalleatis, ultimo subdescendente ; apertura pared, 
obliqua, labro calloso-reflexo. 
THE ALTERED CycLostoma. Shell deeply excavately 
umbilicated, rather discoid, flesh-tinged white, whorls 
narrow, spirally finely ridged above, smooth and 
faintly malleated below, last whorl a little descend- 
ing; aperture small, oblique, lip callously reflected. 
Preirrer, Pro. Zool. Soc. 1851. p. 243. 
Lithidion desciscens, Pfeitter. 
Hab. Island of Socotra. 
A more compactly-whorled species than either of the 
preceding of the Lithidion group, finely ridged above, 
while the under surface is smooth and faintly malleated. 
Species 159. (Mus. Cuming.) 
CYCLOSTOMA EBURNEUM. Cycl. testd latissime aperte um- 
bilicatd, subdiscoided, semipellucido-albd, anfractibus 
subangustis, liris filosis longitudinalibus undique densé 
annulatis ; apertura oblique circulari, labro tenué ea- 
panso-refleco, superne laminato-alato. 
Tue ivory Cyctostoma. Shell very broadly openly 
umbilicated, nearly discoid, semitransparent white, 
whorls rather narrow, densely ringed throughout with 
longitudinal thread-ridges; aperture obliquely cir- 
cular, lip thinly expandedly reflected, laminately 
winged at the upper part. 
Gunptacu, MS. in Mus. Cuming. 
Hab. Cuba. 
This shell has somewhat of the general form of Lithi- 
dion, but it is quite of another type. 
Species 160. (Fig. a, 6, Mus. Cuming.) 
CycLostoma sotutuM. Cycl. testd latissimé ewcavato- 
umbilicatd, depresso-orbiculari, albidd, lineis rufis in- 
terruptis spiraliter pictd, anfractibus subangustis, ro- 
tundatis, liris lonyitudinalibus tenuibus filosis undique 
dense annulatis ; apertura circulari, labro laminato- 
Jimbriato. 
THE LOOSELY WHORLED CycLostoma. Shell very broadly 
excavately umbilicated, depressly orbicular, whitish, 
spirally painted with red interrupted lines, whorls 
rather narrow, rounded, densely ringed throughout 
with longitudinal fine thread-ridges ; aperture cir- 
cular, lip laminately frilled. 
Ricuarp, Pfeiffer, Kiister, Conch. Cab. pl. 39. f. 8-10. 
Choanopoma solutum, Pfeiffer. 
ITab. Haiti. 
The sculpture is like that of the preceding species, but 
the lip has a delicate frill round it, and the shell is banded 
with interrupted red lines. 
Species 161. (Mus. Cuming.) 
CycLostoMA AlaTUM. Cyel. testa subampliter excavato- 
umbilicatd, conoideo-depressd, soliduld, opaco-albd, an- 
Jractibus rotundatis, striis plicato-laminatis undique 
dense annulatis ; apertura rotundata, fauce sanguineo 
marginatd, labro parum reflexo, superne alato. 
Tur wincep CycLostoma. Shell rather largely exca- 
vately umbilicated, conoidly depressed, rather solid, 
opake-white, whorls rounded, everywhere densely 
ringed with plicately-laminated strie; aperture 
rounded, interior edged with blood-red, lip but little 
reflected, winged at the upper part. 
Preirrer, Pro. Zool. Soc. 1851, p. 250. 
Choanopoma alatum, Pfeiffer. E 
Hab. Cuba. 
The ringed sculpture of this species is developed in fine 
plicated laminee. In the aperture is a characteristic 
blood-red circular band. 
