CYCLOPHORIDZ, 97 
Cornu venatorium, Ohemn. Conch. ix. P. ii. p. 104, t. 127, f. 1182, 
33 ? 
Cyclostoma planorbula, Lam. in Encycl. Meth. t. 461, f.3; Lam. 
Hist. vi. p. 143, n. 1, ed. Desh. viii. p. 353; Desh. in Encyel. 
Meth. ii. p. 39.0.1; Desh. Traité élem. Conch. t. 82, f. 3, 4. 
Cyclostoma planorbulum, Vozgt, in Cuv. Thierr. ili. p. 177; Sow. 
when t. 25, 1.633 Pfr. lc. t. 29, f. 16, 173° Petit, in Sourn. 
Conch. i. p. 43. 
Cyclotus planorbulus, Swains. Malac. p. 336; Gray, Cat. Cycl. p. 8, 
n, 14 (part). 
Pterocyclos planorbulus, Pfr. Consp. nu. 47 ; Pneum. Mon. p. 43. 
Hab. Java? Borneo ? 
§ 3. Operculum externally very convex, margin of the whorls form- 
ing a spiral horizontal lamina—Pterocyclos. 
4, Prrrocycios TrRoscHELI. 
Shell orbiculate-depressed ; whorls 4, slowly increasing, the last 
one rather dilated anteriorly ; umbilicus very broad ; peristome 
thickened, reflected, obsoletely sinuate anteriorly and above, 
with a cucullated wing, which is angulated and deflected 
anteriorly, adhering to the penult whorl. Operculum convex, 
horn-coloured. Greatest breadth 20, least br. 18 mill. (B.) 
Pterocyclos Troscheli, Bens. in Ann. & Mag. viii. 1851, Aug. t. 5, 
f.2; Pfr. Consp. n. 48; Pneum. Mon. p. 44. 
Hab. Ceylon, Trincomalee (Bland). 
5. PTEROCYCLOS ANGULIFERUS. 
Shell discoidal, solid, smooth, blackish-chestnut-coloured, with 
irregular white flames ; spire flat ; whorls 5, little convex, the 
last one not descending anteriorly; umbilicus broad ; aperture 
oblique, rather circular, fulvious and pearl]-shining inside; peri- 
stome double ; inner edge shortly expanded, scarcely indented 
above ; external edge white, broadly expanded, dilated above 
near the penult whorl into a blunt beak, which is deeply exca- 
vated beneath. Operculum conic, with 3-4 whorls bearing a 
spiral lamella, and the apex smooth. Height 61, greatest 
breadth 24, least br. 18 mill. 
Cyclostoma angulifera, Sowleyet, in Rev. Zool. 1841, p. 347; Voy. 
de la Bonite, t. 30, f. 6-11. 
Cyclostoma anguliferum, Petzt, in Journ. Conch. i. p. 43. 
Pterocyclos anguliferus, Pfr. in Z. f. M. 1847, p.111; 1851, p. 6; 
Ic. p. 196, t. 24, f. 3-6; Consp. n. 49; Pnewm. Mon. p. 44. 
Hab. Cochin-China. 
