LEPTOPOMA. 
REAmE al: 
Genus LEPTOPOMA, Pfeiffer. 
Testa globoso-turbinata vel conica, tenué calcarea, interdum 
membranacea, anguste, sepe minute, umbilicata, an- 
Jractibus sepissimé spiraliter filoso-liratis ; apertura 
circulari, labro plerumque plano-expanso, juata win- 
bilicum interdum auriculato. Operculum membrana- 
ceum, arctispirum, planum. 
Shell globosely turbinated or conical, thinly calcareous, 
sometimes membranaceous, narrowly often minutely 
umbilicated, whorls mostly spirally thread-ridged ; 
aperture circular, lip generally flatly expanded, some- 
times auriculated next the umbilicus. 
membranaceous, close-spired, flat. 
Operculum 
Under the title Leptopoma, Dr. Pfeiffer includes an in- 
teresting neatly-defined group of the great family Cyclo- 
stomacea, enumerating about fifty species. They have 
mostly thinly calcareous semitransparent shells, some 
opally diaphanous, encircled with characteristic regularity 
by fine rather distant thread-like ridges. One species, Z. 
isigne, is perfectly membranaceous. The ridge marking | 
the periphery of the whorls is mostly developed into a 
keel; there are, however. a few species without ridges or 
keel ; and one, L. vitreum, has been raised to the rank of a 
genus of itself, Dermatocera, Adams. The aperture of the 
shell is circular, and the lip, except in a few abnormal | 
species, is more or less flatly expanded. The operculum 
is entirely membranaceous, closely spired, and flat. 
As in the case of many other genera of this family, the 
geographical distribution of Leptopoma is comparatively 
local. The species are chiefly natives of the islands of 
the Eastern Archipelago, one or two ranging as far as the 
islands of West Polynesia. 
found in India and Ceylon. 
One or two small species are 
Species 1. (Mus. Cuming.) 
LepropoMa Gonrostoma. Lept. testd perangusté umbi- 
licatd, convided, tenui, pellucido-albd, castaneo oblique 
strigatd ; anfractibus declivi-convezis, filis opaco-albis 
distantibus cingulatis, anfractu ultimo ad basin acute 
angulato ; apertura diagonali, subtrigono-ovali, labro 
subexpanso-reflexo, 
THE ANGLE-mMouTH LEpropoma. Shell very narrowly 
umbilicated, conoid, thin, transparent white, obliquely | 
streaked with chestnut; whorls slopingly convex, | 
encircled with distant opake-white threads, last 
whorl sharply angled at the base; aperture diagonal, 
triangularly ovate, lip rather expandedly reflected. 
Cyclostoma goniostoma, Sowerby, Pro. Zool. Soc. 1843, p. 
64. 
Leptopoma goniostoma, Pfeiffer. 
Hab, Cagayan, Province of Misamis, Island of Mindanao, 
Philippines; Cuming. 
A delicate brown-streaked pellucid shel!, encircled with 
distant opake-white threads, that at the angle forming a 
keel. 
Species 2. (Mus. Cuming.) 
Leproroma acumInatuM. Lept. testd minute umbilicatd, 
acuminato-conicd, diaphano-albd, immaculatd, spird 
ewsertd ; anfractibus declivi-convewis, levibus, oblique 
subtilissimé striatis, anfractu ultimo subangulato, ad 
angulum filoso-carinato ; aperturaé diagonali, ovata, 
labro expanso-reflexo. 
THE ACUMINATED Lepropoma. Shell minutely umbili- 
cated, acuminately conical, diaphanous white, un- 
spotted, spire exserted; whorls slopingly convex, 
smooth, obliquely very finely striated, last whorl 
slightly angled, thread-keeled at the angle; aperture 
diagonal, ovate, lip expandedly reflected. 
Cyclostoma acuminatum, Sowerby, Pro. Zool. Soc. 1843, 
p- 65. 
Leptopoma acuminatum, Pfeiffer. 
Hab. St. Juan, Island of Luzon, Philippines; Cuming. 
A semitransparent opal-white shell, with the spire acu- 
minately exserted. 
Species 3. (Mus. Cuming.) 
LEPTOPOMA ELATUM. 
subacuminato-conicd, albidd, fuscescente confertim un- 
dato-strigata ; anfractibus declivi-convexis, levibus, 
ultimo subangulato, ad angulum subobtuse filoso-cari- 
Lept. testd peranguste umbilicatda, 
nato, albido ; aperturd subcirculari, tenueé reflexo. 
THe RAISED Lepropoma. Shell very narrowly umbili- 
cated, somewhat acuminately conical, whitish, closely 
faintly wave-streaked with brown; whorls slopingly 
convex, smooth, last whorl slightly angled, rather 
obtusely thread-keeled and whitish at the angle; 
aperture nearly circular, thinly reflected. 
February, 1862. 
