CYCLOSTOMIDA. 283 
niciDA, Blanford. Shell smooth or spirally striate, imperforate. 
Operculum corneous, subobsoletely multispiral. D. Niligirica, 
Blanf. (1xxv, 67). 
PALAINA, Semper. (Pupoidea, Pease.) First two or three 
whorls much smaller than the others (deciduous?). Opereulum 
membranaceous, multispiral. D. scalariformis, Pease (lxxv, 68). 
CLOSTOPHIS, Benson, 1860. Shell subbiconical ; the penultimate 
whorl large, the last descending, solute, subaxial, small; aperture 
with continuous peristome, and parietal tooth. Operculum 
unknown. WD. Sankeyi, Benson. Caverns near Moulmein. 
MOUSSONIA, Semper. Peristome nearly continuous with a 
tooth upon the centre of the left margin. D. typica, Semper 
(xxv, 69). 
ARINIA, H. and A. Adams. Shell subimperforated, thin, 
smooth, shining, turriculated, obtuse at the summit, last whorl 
swollen; aperture subcircular; margin nearly continuous; colu- 
mellar lip angularly dilated in the middle. Operculum thin, 
calcareous, paucispiral. D. minor, Sowb. (1xxvi, 70). 
OpistHostoMA, Blanford. 
Syn.—Plectostoma, Adams. Scoliostoma, Crespigny. 
Distr.—5 sp. India, Borneo, West Africa. O. Fairbanki, 
Blanford (lxxvi, 71). 
Shell pupiform, umbilicated, with a regular costulated orna- 
mentation ; apical whorls obliquely distorted ; last whorl stran- 
gulated,separated from the others,and applied to the penultimate; 
peristome double, free portion prolonged backwards. Operculum 
horny (?). 
O. De Crespigni, Adams ( Plectostoma), has a conical spire, 
and the apical whorls are not excentric to the axis of the lower 
whorls. 
III. Cyclostomea. 
ADAMSIELLA, Pfeiffer. 
Distr.—16 sp. West Indies. 
Shell pupiform or oblong-turreted ; aperture small, subcireular ; 
peristome usually double, more or less expanded or reflected. 
Operculum thin, rather cartilaginous, whorls few, with subcen- 
tral nucleus. A. mirabilis, Wood (1xxvi, 72). 
Dipetopoma, Pfeiffer. 
Distr.—D. architectonicum, Gundl. (Ixxvi, 73, 74). 
Shell oblong-turreted. Operculum subduplicate, acutely 
separated at the margin; inner layer concave, smooth; outer 
layer inflated, caleareous, paucispiral, nucleus profoundly 
immersed. 
