

HELIX- JACOSTA. 183 



very little convex ; the apex small, smooth, hardly projecting. 

 Whorls six, very slowly increasing, encircled by a projecting and 

 serrate carina, which the regularly impressed suture follows. The 

 last whorl is slightly dilated, nearly flat above, with an impressed 

 groove above the carina; swollen and subangulate around the 

 umbilicus; slightly but distinctly descending in front. Aperture 

 oblique, compressed ovate-acuminate in form, slightly lunate, out- 

 wardly channelled ; peristome thin, acute, without visible lip within ; 

 outwardly angulate; upper lip little rounded, the basal lip more 

 strongly rounded, hardly dilated at the insertion. (j5To>.) 



Alt. 4, greater diam. 11 J, lesser 10 mill. 



Dschebel Zaghuan and Dschebel Rsass, northern Tunis. 



H. zeugitana L. & B., Prodr. Mai. Tunisie, p. 93. H. (Jacosta) 

 zeugitana KOB., in Rossm. Icon. n. f. iv, p. 20, f. 537. 



H. PONSONBYI Kobelt. PI. 40, figs. 61, 62. 



Shell rather narrowly but deeply umbilicate, depressed trochiform 

 carinated, rather solid, dull ashy-white ; spotted with brown at the 

 sutures, and ornamented with four or five narrow lines at the base 

 and a reddish-brown band above the carina. Whorls five, nearly 

 flat, rib striated, regularly increasing, the last whorl dilated, more 

 convex, distinctly ribbed, encircled at the periphery with a white 

 serrated carina, above which it is impressed ; base flattened, rect- 

 angularly passing into the umbilicus ; slightly deflexed in front. 

 Aperture transversely ovate, distinctly angulate at the carina, the 

 margins hardly converging; upper margin produced, lower margin 

 having a distinct, deep seated brown lip, and slightly dilated at the 

 insertion. (Kob.) 



Alt. 5, greater diam. 10, lesser 9 mill. 



Or an, Algeria, on cliffs ; solitary and not easy to find. 



H.ponsonbyi KOB., Jahrb. D. M. Ges. ix, 1882, p. 18 ; Rossm. n. 

 f. iv, p. 21, f. 538. 



This species forms a transition from the southern Spain group of 

 H. derogata to the group of H. amanda. 



H. BARNEYANA Ancey. PI. 44, figs. 90, 91. 



Shell depressed, narrowly umbilicated (the umbilicus contained 

 about 12 times in the diameter of the shell) ; solid, opaque, chalk- 

 white, more or less mottled with translucent, and having a narrow 

 chestnut or translucent band above and a broad one below the periph- 

 ery. There are often several additional brown bands developed on 



