36 TERRESTRIAL MOLLUSCA INHABITING SOCIETY ISLANDS. 
undulately striped with chestnut-brown. The revolving striae are sometimes nearly 
obsolete. 
€ 
Diam. 5-54, height 24-34 mill. 
L. GREGARIA, Garrett, Plate IT, figs. 6, 6 a, 6 b. 
Shell small, umbilicated, solid, orbicular, depressed, not shining, closely and 
obliquely striated with small, regular, slightly biarcuate, rough riblets, which are more 
crowded on the base ; whitish corneous, tessellated and undulately rayed with chestnut- 
brown ; spire depressed dome-shaped, apex flattened; suture moderately impressed ; 
whorls seven, slightly convex, narrow, slowly and regularly increasing, last one acutely 
carinated, sometimes descending a little below the penultimate whorl; base flatly 
convex, concave on the boundaries of the umbilicus; umbilicus (in adolescence) wide, 
exposing all the whorls, one-third the major diameter of the shell; in adults strongly 
constricted by an acute expansion of the last whorl; aperture small, oblique, 
depressed, irregular rhomboid-luniform; lamin 5-6, two in the parietal region, 
elongate, of equal length, one columellar, two in the palate beneath the keel, 
short, conspicuous, one above the keel, inconspicuous and occasionally absent; peris- 
tome acute, straight, basal margin continuous with the acute umbilical constriction ; 
columella short, concave, receding. 
Major diam, 7, height 34 mill. 
Hab.—Moorea. 
I discovered two colonies of this very distinct species in two valleys on the south- 
west part of Moorea. They were congregating in immense numbers on the under side 
of loose stones. Though carefully searched for, I failed to detect them in any other 
part of the island. No other species of this genus occurs in the same location with 
the shells under consideration. 
With the exception of a slight difference in the elevation of the spire, they are 
very uniform in all their specific characters. 
L. RECEDENS, Garrett. Plate II, fig. 7. 
Shell small, umbilicated, not shining, rather solid, depressed, orbicular, with thin, 
crowded, slightly oblique, rough, elevated strive, which are finer and more closely set 
on the base; dark chocolate-brown, with or without yellowish horn-colored tessellations 
and undulated stripes; spire depressly convex, apex flattened ; suture linearly 
impressed ; whorls seven, very little convex, narrow, slowly and regularly increasing, 
last one carinated, gradually descending below the periphery of the penultimate 
whorl; base convex, concavely indented at the axis; umbilicus (in adolescence) freely 
exposing all the whorls, a little more than one-third the greater diameter of the 
shell; in adults the umbilicus is constricted to about one-third that of adolescent 
examples ; aperture small, depressed, oblique, irregularly rhomboid-luniform ; laminie 
six, two on the parietal region, elongate, the lower one deeply seated, a stout one on 
