RIEBECKIA. 



209- 



increasing, separated by a deep oblique suture, the two apical 

 smooth, convex, tabulate above, forming an obtuse apex, the 

 following 5-6 somewhat convex, the rest less convex, flattish, 

 sculptured with slightly oblique striae, close and peculiarly 

 crenulated, the last angulated at the periphery, not descend- 

 ing; aperture angularly oval; peristome slender, simple; 

 columellar margin narrowly reflexed. 



'* Length 37, diameter 6 mm.; aperture 5 mm. long and 3 

 broad." (Smith). 



Sokotra (Mrs. Bent). 



Stenogyra (Riebeckia) insculpta SMITH, Journ. of Mala- 

 cology vi, p. 37, pi. 5, f. 7 (Jan. 22, 1898) ; Nat. Hist. So- 

 kotra, p. 136, fig. 



' ' This species is remarkable for the peculiar sculpture, con- 

 sisting of close-set slightly oblique raised lines of growth, 

 which being crossed by numerous transverse impressed striae, 

 have a prettily festooned or crenulated appearance. It differs 

 from S. arguta Martens, in sculpture, in the angulation of the 

 body- whorl and more tapering form." (Smith). 



7. R. ARGUTA (Martens). PI. 55, figs. 89, 90. 



Shell subulate-turrited, perforate, closely sharply vertically 

 fltriate; white, usually with a ferruginous incrustation. 

 Whorls 11, the first two forming an obtuse apex, smooth, the 

 following regularly increasing, the upper whorls rather con- 

 vex, the lower ones flattened, suture moderately impressed. 

 Aperture occupying one- fourth the total length; outer mar- 

 gin thin, little arcuate; columellar margin reflexed, spirally 

 entering above, tapering downwards. Length 20, diam. 5, 

 length of aperture 5, width 3 mm. (v. Marts.) 



Sokotra: Wady Kischen at 650 meters elev., and above up 

 to 1000 meters, in crevices in the granite. Also at Keregnigi 

 (Riebeck and Schweinf urth) . Hadibu plain; Adho Dimel- 

 lus, 3500-4500 ft.; Homhil, 1500-2500 ft. (Forbes exped.). 



Stenogyra arguta v. MARTENS, Nachrbl. D. mal. Ges. 1881, 

 p. 138; Conch. Mittheil. ii, p. 149, pi. 28, f. 17, 18 S. (R.) 

 arguta SMITH Nat. Hist. Sokotra, p. 136. Stenogyra Jessica 

 GODWIN-AUSTEN, P. Z. S., 1881, p. 810, pi. 69, f. 3. Steno- 



