296 CATALOGUE OF PHANEROPNEUMONA. 
furnished with two keels on the periphery; aperture rather 
triangular; peristome slightly reflexed; columella angulated at 
its base covered with copious callus. Height }, breadth § inch. 
Helicina trochlea, Gould, in Proc. Bost. Soc. 1847, p. 202; Exped. 
Shells, p. 36, ed. 1851, p. 99, f. 109; Pfr. Pneum. Mon. p. 404. 
Hab. The island of Matea. 
V. ALCADIA. 
Operculum not spiral, rather solid, semiovate, furnished at its 
lower extremity with a tooth-like appendage. Shell heliciform, 
turbinate, subglobose or slightly depressed, for the most part 
hairy, covered with callus round the columella, which is flat- 
tened, nearly rectilinear. Aperture semiovate, rather trian- 
gular; peristome more or less expanded, separated from the 
columella by a distinct, for the most part curved slit. 
Alcadia, Gray, Syn. Brit. Mus. 1840, p. 134, ed. 1842, p. 91; Proc. 
Z. S. 1847, p. 182, n. 533; Sow. Conch. Man. ed. il. p. 61; Pfr. 
Pneum. Mon. p. 404. 
Helicina (part), Swainson, Malacol. p. 337. 
Helicina, § 6, Pfr. in Z. f. M. 1848, p. 83. 
Helicina sp., Auct. 
1, ALCADIA MAJOR. B. M. 
Shell depressed-globose, solid, nearly smooth, marked with rows of 
very minute points, slightly shining, fuscous-reddish or yellow ; 
spire short, conoidal; whorls scarcely 5, moderately convex, 
last rounded; aperture semiovate; columella arcuated forward 
at its lower extremity, separated from the peristome by a short, 
distinct slit; peristome thickened, expanded ; basal callus thick, 
diffused. Operculum shelly, rather concave and pale on the 
outer side. Height 15, greatest breadth 22, least br. 18 mill. 
Helicina major, Gray, in Zool. Journ. i. p. 68, t. 6, f. 10; Désh. in 
Lam. Hist. viii. p. 162, n. 14; Sowerby, Genera of Shells, n. 36, 
f.1; Sow. Conch. Man. f.306; Reeve, Conch. Syst, t. 186, f. 7; 
Sow. Thes. nu. 13, p. 4, t. 1, f. 12,13; Pfr. Ic. n. 28, p. 27, t. 6, 
£1, 2. 
Alcadia major, Gray, in Proc. Z. S. 1847, p. 182; Pfr. Pneum. 
Mon. p. 405. 
Hab, Jamaica (Adams). 
2. ALCADIA HIRSUTA. 
Shell depressed-globose, rather thin, brownish-red, with an hirsute 
brownish epidermis, having long hairs in six spiral lines, of 
which one is next below the suture, and the others are on the 
