1881.] SHELLS FROM SOCOTRA. 256 



Otopoma clathratulum, var. minor. 



Sliell closely umbilicated, very globosely turbinate, solid, polished, 

 sculpture regular spiral ribbing, crossed by fine transverse irregular 

 costulation ; colour white, one specimen dark grey on the apex ; 

 spire conoid, apex blunt, and smooth for Ig whorl ; whorls 4| ; 

 aperture ovate ; peristome simple, strong, and attached close to the 

 penultimate whorl. Operculum situated close to the peristome, very 

 thick and shelly, the subcentral nucleus slightly sunken below the 

 outer whorl ; dark grey in central portion. 



Size : — 



Major diani. 0*54, minor diam. 0-40, alt. axis 0*40 inch. 

 „ ,, 18-0 „ „ 15-3, „ „ 16-6 millims. 



["On plain near GuUonsir village, very common." (I. B. B.) The 

 greater number, however, are marked " very common, from the plain 

 in vicinity of Kadhab."] 



This shell is very similar to the last, but only about half the size ; 

 and the difference in the position of the peristome with respect to 

 the penultimale whorl is very marked and constant. 



Otopoma conicum, n. sp. (Plate XXVIII. fig. 1.) 



Shell conoid, closely umbilicated, solid ; sculpture fine, regularly 

 disposed spiral ribbing crossed by fine costulation, continued to well 

 within the umbilical region ; colour white ; spire conic, sides rather 

 flat, apex subacute ; suture rather shallow ; whorls 5, the last well 

 rounded, slightly descending, aperture circular, suboblique ; peri- 

 stome very thin; columellar margin simple, not reflected. Operculum 

 shelly, solid, paucispiral, of 3 whorls, smooth subcentral nucleus 

 depressed, concave behind. 



Size :— 



Major diam. 0-24, minor diam. 0-20, alt. axis 0'32 inch. 

 „ „ ll'O, „ „ 10-0, „ „ 7-0 miUims. 



[" From the plain about GoUonsir village." (I. B. B.)] 



Otopoma turbinatum, n. sp. (Plate XXVIII. fig. 2.) 



Shell turbinate, umbilicated ; sculpture regular, fine, equally 



distributed, spiral ribbing smooth on the last whorl near umbilicus ; 



apex smooth ; colour white ; spire pyramidal, suture impressed ; 



whorls 4 1, well rounded ; aperture nearly circular, slightly angular 



above ; peristome thin, much curved on the columellar margin. 



Operculum not obtained. 

 Size : — 



Major diam. 88, minor diam., 7-9, alt. axis 5-0 millims. 

 „ 0-35, „ „ 0-33. „ „ 0-23 inch. 



[" On stems of Dracccna cinmbari, Balf. fil., at 20(t0 feet eleva- 

 tion, on limestone." (I. B. B.).] Only three specimens were 

 obtained. 



TROPiDoriioiiA socotrana, n. sp. (Plate XXVIII. fig. 3.) 

 Shell trochiform, umbilicated, rather solid; sculpture three strong 



