CYCLOPHORID A. 87 
IX: MEGALOMASTOMA. 
Operculum orbicular, thin, horny, many-whorled, rather flat. Shell 
narrowly or scarcely perforate, oblong turreted or pupa-shaped ; 
aperture rather circular, sometimes furnished with a slight 
lateral channel; peristome double or simple, rather thickened, 
rarely straight. 
Megalomastoma, G'uilding, in Swains. Malac. p. 186, 336; Pfr. in 
Z. £. M. 1847, p. 109; 1851, p.148; Consp. p.20; Gray, in Prec. 
Z. S. 1847, p. 182; Cat. Cycl. p. 30; Pfr. Mon. Pneum. p. 128. 
Farcimen, J'roschel, in Z. f. M. 1847, p. 44; Gray, in Proe. Z. 8. 
1847, p. 182; Cat. Cycl. p. 28. 
Cyclostomatis sp., Awuctt. 
A. Peristome straight . ’ : Sh Riunge 
‘ expanded. 
1. ''hickened ‘ oc 8 Qala sys Se 
2. Rather thin, usually double . $3. ,, 12-19. 
§ 1. Peristome straight. 
1. MEGALOMASTOMA CYLINDRACEUM. B. M. 
Shell arcuately rimate, cylindrical, solid, slightly striate longitu- 
dinally, saffron-coloured; spire elongate, lessened towards the 
apex, which usually is slightly truncate; whorls 8, rather flat- 
tened, last somewhat compressed beneath, sometimes anteriorly 
dark violaceous; aperture nearly perpendicular, rather circular, 
yellow, with a saifron-coloured ring; peristome simple, con- 
tinued, straight, slightly thickened, thicker and somewhat de- 
tached at its upper angle. Length 34, breadth 105 mill. 
Helix cylindracea, Chemn. Conch. Cab. ix. part il. p. 166, t. 135, 
f. 1233. 
Helix crocea, G'mel. Syst. p. 3655, n. 243. 
Turbo croceus, Dillw. Descr. Catal. ii. p. 862, n. 112. 
Turbo flavidus, Wood, Ind. Suppl. t. 6, f. 31. 
Cyclostoma flavula, Zam. Hist. vi. p. 146, n. 13 (Eneyel. méth. 
t. 461, f. 62), ed. Desh. viii. p. 357; Desh. in Encycl. méth. ii. 
p- 41, 0.8; Webb & Berth, Synops. Canar. n. 31; Chenu, Ll. 
Conch. t. i. f. 17. 
Cyclostoma flavidum, Gray, in Wood, Suppl. p. 36. 
Cyclostoma crocea, Desh. in Lam. ed. alt. viil. p. 357. 
Cyclostoma . . . Sow. Consp. Man. f. 529. 
Cyclostoma flavula, Sow. Thes. n. 53, p. 108, t. 24, f. 66, 67. 
Cyclostoma cylindraceum, Pfr. Jc. n. 116, p. 114, t. 17, f. 1-3. 
Cyclostoma croceum, Petit, in Journ. Conch. i. p. 45. 
Megalomastoma flavula, Swains. Malac. p. 336. 
