CYCLOSTOMID^. 283 



NiciDA, Blanford. Shell smooth or spirally striate, imperforate. 

 Operculum corneous, subobsoletely multispiral. JD. Niligirica^ 

 Blauf. (Ixxv, 67). 



PALAiNA, Semper. (Pupoiclea, Pease.) First two or three 

 whorls much smaller than the others (deciduous ?). Operculum 

 membranaceous, multispiral. D. scalar if or mis, Pease (^Ixxv, 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. D. Sankeyi, Benson. Caverns near Moulmein. 



MoussoNiA, Semper. Peristome nearly continuous Avith a 

 tooth upon the centre of the left margin. D. typica, Semper 

 (Ixxv, 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. (Ixxvi, TO). 



Opisthostoma, Blanford. 



Syn. — Plectostoma, Adams. Scoliostoma, Crespigny. 



Distr. — 5 sp. India, Borneo, West Africa. 0. Fairhanki, 

 Blanford (Ixxvi, 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 (?). 



0. De G respigni, Adavas (Plectostoma), has a conical spire, 

 and the apical whorls are not exeentric to the axis of the lower 

 whorls. 



III. Cyclostomea. 



Adamsiella, Pfeiffer. 



Distr. — 16 sp. West Indies. 



Shell pupiform or oblong-turreted ; aperture small, subcircular ; 

 peristome usually double, more or less expanded or reflected. 

 Operculum thin, rather cartilaginous, whorls few, with subcen- 

 tral nucleus. A. mirabilis, Wood (Ixxvi, 72). 



DiPLOPOMA, 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, calcareous, paucispiral, nucleus profoundly 

 immersed. 



