182 CATALOGUE OF PHANEROPNEUMONA. z 
XXIV. CISTULA. 
Operculum, ovate, thin, cartilaginous, with a thin external shelly 
coat, with few gradually-increasing whorls, the margin of which 
is usually detached; nucleus excentrical. Shell globose-conic, 
or ovate or oblong-turreted, usually truncate; aperture ovate; 
peristome simple, expanded, or double. 
Cistula, Gray, Catal. Cycloph. p. 57 (part); Pfr. in Z. f. J. 1851, 
p. 169; Consp. p. 41; Pneuwm. Mon. p. 260. 
Choanopoma (sp.), Gray. 
Cyclostoma (sp.), Auctorwm. 
A. Globose-conic : ; : oS SS ee 
B. Ovate or oblong-turreted. 
1. Last whorl not detached. 
a. Peristome simple .-. : ee ea 
6. Peristome double. 
a. Outer edge dilated . ‘ Ma SRP cc 
B. Outer edge narrow . : JQ ao aie 
2. Last whorl detached anteriorly. 
a. Peristome rather simple . 2 (0 ab Goes 
6. Peristome distinctly double. 
a. Outer edge flat . ; ; pik 
B. Outer edge fringed . : fy 
bn er) 
i) 
ie 
bo 
ee) 
§ 1. Shell globose-conical. 
1. CistuLA ? PLATYCHILA. 
Shell perforate, ovate-conic, truncate, rather thin, smooth, dia- 
phanous, glassy-white; whorls remaining 4, convex, increasing 
gradually, the last one grooved obsoletely and spirally beneath ; 
aperture perpendicular, ovate; peristome double; inner edge 
slightly expanded, not prominent, outer edge somewhat thick- 
ened, broadly spreading angularly, with the margins angularly 
joined, on the penultimate whorl, by a small callus, columellar 
margin in the middle produced into an angle. Length 26, 
breadth 16 mill. 
Cyclostoma latilabre, Pfr. Jc. n. 72, p. 78, t. 10, f. 26,27. Not 
Orbigny. 
Cyclostoma platychilum, Pfr. JZSS. 
Cistula ? platychila, Pfr. Consp. n. 380; Pneum. Mon. p. 261. 
Locality unknown. 
9, CISTULA CATENATA. B. M. 
Shell umbilicate, globose-turbinate, thin, sculptured with crowded, 
more or less raised, spiral lines, pale reddish-horn-coloured, 
