28 CATALOGUE OF PHANEROPNEUMONA. 
6. PrEROCYCLOS TENUILABIATUS. 
Shell depressed, subdiscoidal, solid, striate, and with transverse 
impressions on all sides, brownish, marmorated with darker 
chestnut-coloured angulose stripes; spire flat, rather concave, 
with the apex a little prominent; whorls 41, moderately convex, 
rapidly increasing, the last one rather depressed ; umbilicus 
broad ; aperture diagonal, nearly circular; peristome double ; 
internal edge shortly produced, a little indented above; ex- 
ternal edge nearly continued, white, with the columellar margin 
shortly reflected; right margin dilated, expanded; upper margin 
raised like a cap near the penult whorl. Operc.? Height 64, 
greatest breadth 26, least br. 21 mill. 
Cyclostoma tenuilabiatum, Metcalfe, in Proc. Z. S. 1851. 
Pterocyclos tenuilabiatus, Pfr. Consp. n. 50; Pnewm. Mon. p. 45. 
Hab. Borneo. 
7. Prmrocycitos ALBERSI. 
Shell discoidal, rather solid, slightly striate, white, marbled with 
chestnut-coloured stripes, and with a broad blackish band below 
the periphery, with a horn-coloured periostraca; spire scarcely 
raised in the middle; suture deeply channelled; whorls 5, 
rather flattened, the last one disjoined anteriorly, with a scaly 
keel above; umbilicus very broad; aperture nearly circular, 
whitish inside; peristome double; internal edge straight, a 
little prominent and expanded, deeply indented above; external 
edge somewhat thickened, expanded, produced above into a 
beak, which is curved forward, quite disjoined and continued 
backwards into the channel of the suture. Operculum with a 
flat smooth apex ; spiral lamella of the lower whorls coronated 
with crowded raised spines. Height 9, greatest breadth 26, 
least br. 22 mill. 
Pterocyclos Albersi, Pfr. in Z. f. M. 1847, p. 151; Ic. p. 197, t. 28, 
f.1-5; Gray, Cat. Cycl. p. 12, n.4; Pfr. Consp. n. 51; Pneum. 
Mon. p. 45. 
Cyclostoma Albersi, Petit, in Journ. Conch. 1. p. 43. 
Locality unknown. 
8. PrERocycLos HISPIDUS. B. M. 
Shell discoidal, solid, very minutely decussate by the striz of 
growth, and crowded, raised, concentric lines, white, covered 
with a spinulose periostraca of a greenish-brown colour with 
darker lines; spire flat; whorls 53, rather depressed, the last 
one descending anteriorly, bearing at a distance of 7-8 mill. 
behind the aperture a triangular beak, which is scarcely opened, 
recurved and touching the suture; umbilicus broad; aperture 
