34 CATALOGUE OF PHANEROPNEUMONA. 
b. Operculum horny, thin, without any external shelly layer. Shell 
conical or depressed ; last whorl rounded, without any groove or rudge 
round the fossils of the axis. Cyclophorina, Gray. 
IV. AULOPOMA. 
Operculum horny, with many whorls, planorbis-shaped, composed 
of two plates, betwixt which it has a spiral channel, which is 
interiorly open on the last whorl. Shell turbinate-depressed, or 
discoidal, the last whorl disjoined anteriorly ; peristome free, 
straight, continuous, immersed in the circular groove of the 
operculum. 
Aulopoma, 7voschel, in Z. f. M. 1847, p. 43; Pfr. ibid. p. 110; 
1851, p. 137; Consp. p.9; Gray, Cat. Cyel. p. 14; Pfr. Pnewm. 
Mon. p. 52. 
Cyclostoma sp., Sowerby, Guerin, ete. 
The outer layer of the operculum generally covers the edge of 
the peristome of dead shell, but in the living state, when flexible, 
it can be drawn into cavity like other opercula. (Gray.) 
1. Autopoma I 1eERI, B. M. 
Shell depressed, nearly discoidal, solid, slightly striate, whitish, 
the whole surface being generally covered with a greenish- 
brown periostraca ; spire mucronate, blueish-black ; whorls 443, 
cylindrical, the last one descending and disjoined anteriorly ; 
umbilicus broad; aperture oblique, circular; peristome con- 
tinuous, straight, sharp. Operce. typical, with 5 distantly striate 
whorls. Height 11, greatest breadth 22, least br. 18 mill. 
Cyclostoma Itierii, Guérin, in Revue, Zool. 1847, p.1; Petit, wm 
Journ. Conch. i. p. 43. 
Cyclostoma cornu venatorium, Pfr. Jc. n. 173, p. 159, t. 22, f. 1-3. 
Cyclostoma Hoffmeisteri, Benson, in Ann. & Mag. 2nd ser. vil. 
p. 265. 
Aulopoma Hofmeisteri, Trosch. in Z. f. I. 1847, p. 43; Gray, Cat. 
Cycl. p. 14, n. 4. 
Aulopoma cornu venatorium, Gray, Cat. Cycl. p. 14, n. 1. 
Aulopoma Itierii, Gray, Cat. Cycl. p. 14, n. 3; Pfr. Consp. n. 62; 
Pneum. Mon. p. 52. 
Hab. Ceylon. 
2, AULOPOMA ? CORNU VENATORIUM. 
Shell orbicular, depressed, whitish ; spire mucronated, with a black 
apex; volutions 4, ventricose, transversely striated on the 
upper part, smooth beneath, with a brown spiral line in the 
middle ; suture deep ; aperture circular ; peritreme thin, acute; 
umbilicus very large. Height 11, breadth 20 mill. (Sow.) 
SS 
