CYCLOPHORIDSA. 11 
10, CycLoTUS SEMISTRIATUS. B. M. 
Shell turbinate-depressed, rather thin, upper side with crowded 
minute spiral lines, whitish, brownish-marmorate ; lower side 
smooth, whitish, with fine spiral furrows in the umbilicus, 
which is moderately large; spire conoidal, rather acuminate; 
whorls 4-5, rounded, the last one scarcely descending anteriorly ; 
aperture oblique, ovate-rounded ; peristome straight, sharp; its 
margins on the penult whorl angularly joined by a short callus; 
right margin a little sinuate; columellar margin a little re- 
flexed. Operc.? Height 83, greatest breadth 133, least br. 
11 mill. 
Cyclostoma semistriatum, Sow. in Proc. Z. S. 1843, p. 29; Thes. 
p. 91, n. 3, t. 23, £. 6; Pfr. Ic. p. 147, n. 156, t. 20, f. 10-12. 
Cyclostoma fasciatum, Hutt. Mss. in Mus. Brit. 
Cyclostoma album, Hutt. in Mus. Brit. 
Aperostoma semistriatum, Pfr. in Z. f. M. 1847, p. 104. 
Cyclotus semistriatus, Gray, Cat. Cycl. p. 10, n. 26; Pfr. Consp. 
n, 10; Mon. p. 22. 
Hab. India, Poonah and Neemuch; also Ceylon ? 
1]. CychoTus PROMINULUS. B. M. 
Shell depressed, nearly discoidal, thin, with somewhat wrinkled 
oblique striz, not shining, white; spire shortly raised, with a 
fine prominent apex ; whorls 4-5, convex, rapidly increasing, 
the last one depressed, dilated anteriorly and generally dis- 
jomed from the penult whorl; umbilicus large; aperture 
scarcely oblique, nearly circular; peristome straight, sharp, 
continued, or shortly interrupted, with the margins joined by a 
shining callus. Operculum with very narrow whorls, the mar- 
gins of which are acutely raised. Height 8, greatest breadth 15, 
least br. 12 mill. 
Cyclostoma prominulum, Fer. Mus.; Orb. Voy. Amér. p. 362, 1837. 
Cyclostoma planorbulum, Sow. Conch. Man. ed. ii. f. 530 2 
Cyclostoma Brasiliense, Sow. Spec. Conch. Pt. ii. Cyclost. £.8 ; Zool. of 
Beechey’s Voy. p. 147, t. 38, f. 32; Proc. ZS. 1843, p. 29; Thes. 
p. 92, n. 4, t.23, £7; Pfr. Ic. p. 108, n. 108, t. 12, £. 13-15. 
Aperostoma Brasiliense, Pfr. in Z. f. M. 1847, p. 104. 
Cyclotus Brasiliensis, Gray, Cat. Cycl. p. 6, n. 4; Pfr. Consp. n. 11. 
Cyclotus prominulus, Pfr. Mon. Pneum. p. 28. 
Hab. Brazils ; near Rio Janeiro and in Minas Geraes. 
12. CycLoTUS SUTURALIS. B. M. 
Shell discoidal, rather thin, slightly striate, greenish horn-coloured ; 
spire scarcely prominent, with a fine apex ; suture deep, chan- 
