806 MR. H. B. PRESTON ON NEW GENERA AND 
median region ; labrum acute, receding below, advancing above ; 
aperture subrectangular. 
Alt. 7, diam. maj. 6°25, diam. min. 6 mm. 
Aperture: alt, 3, diam. 2°5 mm. 
Hab. Urguess, British East Africa. (A. Blayney Percival.) 
PERCIVALIA, gen. nov. 
Shell thin, perforate, compactly coiled, turbinate, sculptured 
on the spire with transverse wrinkle-like plications, which are 
absent on the bases. 
Genotype: P. nyiroénsis Preston. 
PERCIVALIA NYIROENSIS, sp.n. (Pl. L. figs. 12 a, 12d.) 
Shell depressedly turbinate, polished, shining, pale greenish 
yellow, painted with a broad, supersutural, spiral band of chestnut, 
which appears as a superperipheral band on the last whorl ; 
whorls 6, the first two slightly exserted, the remainder flattish, 
the last angular at the periphery, sculptured with oblique, trans- 
verse, arcuate, wrinkle like plice; suture impressed, narrowly 
margined above; base of shell somewhat convex, sculptured only 
with very fine, indistinct, wavy, spiral striz; umbilicus very 
narrow, partly concealed by the twisted columella; columella 
somewhat sharply twisted above, very obliquely descending ; 
labrum simple; aperture rather obliquely sublunate. 
Alt. 6, diam. maj. 10, diam. min. 9°25 mm. 
Aperture: alt. 5, diam. 4°75 mm. 
Hab. Mount Nyiro, to the south of Lake Rudolph, at an 
altitude of 8300 feet. (A. Blayney Percival.) 
LEDOULXIA CRASSIPLICATA, sp.n. (PI. I. figs. 1, 1a.) 
Shell depressedly turbinate, thin, light brown; whorls 5, 
regularly increasing, convex, shouldered above, sculptured with 
coarse, rather distant, obliquely arcuate, somewhat acute plications, 
the last whorl acutely and callously carinate at the periphery ; 
suture impressed, narrowly callously margined above; base of 
shell moderately convex, smooth, without sculpture ; umbilicus 
open, deep, sculptured with somewhat distant, wavy, revolving 
strie within ; columella margin broadly outwardly expanded and 
vertically descending above, curved below; labrum simple ; 
aperture obliquely subrectangular. 
Alt. 7, diam. maj. 11:5, diam. min. 10 mm. 
Aperture: alt. 5, diam. 4°5 mm. 
Hab. Forest to the north of Mount Kenia, British East Africa. 
(A. Blayney Percival.) 
LEDOULXIA DECUSSATA, sp. n. (PI. I. fig. 7.) 
Shell with roundly turbinate spire, pale brownish yellow above, 
the colouring concentrating in an ill-defined, supersutural, reddish- 
brown band, showing traces of having been covered with a 
