258 PERUSSACIA, SECTION PEGEA. 



mit; apex paler, stout. Whorls 6, all irregularly increasing, 

 separated by a paler, duplicated, superficial suture, the last half 

 the total length, convex, rather dilated on the right side. 

 Aperture long, acutely angular above, rather dilated below, 

 with a deeply-placed very minute parietal lamella. Columella 

 short, whitish, straight, lamellar, denticulate in the upper part. 

 Peristome unexpanded, acute, whitish, outer margin produced 

 forward, margins joined by a thin callus. Length 9.5, diam. 

 2.5 mm. (Bgt.). 



Algeria: Mouth of the Cheliff, prov. Oran. 



F. subgracilenta BGT. , Species noviss. , etc., p. 34, 1876. 



"This Ferussacia is especially characterized by the irregu- 

 larity of its whorls. The first whorl is regular; the second is 

 wide on the right, narrow on the left side; the third, inversely, 

 is narrow on the right, wide on the left; the fourth, narrow on 

 the right, is excessively developed on the left; finally the last 

 two are much lengthened and follow a descending direction, the 

 descent especially rapid between the fourth and penult whorls 



' ; 



47. F. ABIA Bourguignat. PI. 44, fig. 18. 



Shell minute, lanceolate, cylindric, very slender, glossy, 

 pellucid, smooth, buff-corneous. Spire attenuate, the apex a 

 little obtuse. Whorls 6, flattened, the first 3 regularly and 

 slowly widening, fourth larger, more rapidly increasing, a little 

 more convex on the left side, the rest larger; suture pale, super- 

 ficially duplicated; last whorl rather convex, over one-third the 

 total length. Aperture oblong-piriform, with a deep-seated 

 whitish parietal lamella. Columella whitish, straight, lamellar 

 within and generally calloused above. Peristome acute, un- 

 expanded ; outer margin strongly arched forward, margins 

 joined by a thin callus. Length 7, diam. 2, aperture 3 mm. 



Algeria : common around Algiers, etc. Tunis: Oued Sidi- 

 Aich. 



F. abia BGT., Malac. de 1'Algerie ii, p. 65, pi. 4, f. 31-34 

 (1864); Prodr. Malac. Tunisie p. 125. KOBELT, Iconogr., vii, 

 p. 29, pi. 187, f. 1185. 



