30 HELICID A. 
and impressed sutures; last whorl narrow, not descending in 
front; aperture slightly oblique, rounded-lunate; peristome 
simple, acute, margins joined. H. dissimilis, Orb. South 
America. 
Macrocycloides, Martens, 1867. Shell depressed, almost 
planorboid, shining, striate, hyaline, base slightly excavated, 
showing all the whorls; peristome acute, the margins slightly 
approaching. HH. obscurata, Ad. and Reeve. 3sp. East Indies. 
Pitys, Beck, 1837. (Endodonta, Albers, 1850.) Shell small 
or minute, corneous, frequently with longitudinal brown bands, 
umbilicated or rarely subperforated; conical, orbicular, depressed 
or discoidal; aperture lunar, angular, very rarely rounded, with 
lamellar teeth upon the interior or parietal walls, or both ; peris- 
tome simple, sharp. 56 sp. Polynesia. H. lamellosa, Fer. 
H. contorta, Fer. (xciv, 11). Sandwich Islands. 
Libera, Garrett, 1881. Shell small, widely umbilicated, umbil- 
icus (in adults) strongly constricted, so as to form a cavernous 
or pouch-like cavity; whorls 7—9, costulate or striate, last one 
angulate or carinate, rarely rounded ; peristome simple; parietal 
region with one or two, and the palate with two or three internal 
Jamine ; columella emarginate and furnished with a spiral fold. 
Polynesia. H. fratercula, Pease. Remarkable for their singular 
habit of ovipositing into their cavernous umbilicus—the con- 
striction. of which does not occur until the last two whorls are 
completed. Sometimes a temporary shelly plate retains the eggs 
or young within the umbilicus. 
Laoma, Gray, 1849. Shell turreted, conical, scarcely per- 
forated, smooth, pellucid, shining; whorls seven, flattened, the last 
carinated, base plane; aperture square depressed, lamellate ; lip 
simple. H. leimonias, Gray. 2 sp. 
Charopa, Albers, 1860. Shell thin, depressed, rarely conical, 
umbilicated, with transverse ribs, sparsely bristly ; whorls 4-54, 
the last not deflected in front ; aperture slightly oblique, lunately 
rounded; peristome simple, margins joined. H. coma, Gray 
(xciv, 12); New Zealand. 48 sp.; Australasia. 
Trochomorpha, Albers, 1850. (Geotrochus, Van Hasselt.) 
Shell umbilicated or subperforated, trochiform, the apex more 
or less obtuse; whorls somewhat flattened, the last with a 
earinated periphery; aperture depressed, oblique ; peristome 
simple; columellar lip rarely thickened or dentate. 165 sp. 
India, East Indies, Polynesia. 
Nigritella, Albers, 1860. Depressed trochiform, umbilicated, 
striate, shining, dark brown or blackish; whorls 7-8, the last 
plane or excavated beneath; aperture depressed, oblique, semi- 
oval or elliptical; peristome simple, thickened, outer margin 
flexuous, columellar margin callous. H. nigritella, Fer. #4. 
Pagodula, Pfr. (xciii, 4). 
