240 FERUSSACIA, SECTION PEGEA. 



Cylindric-fusiform shells with conic spire and a rather long, 

 piriform aperture which is longer and narrower above than 

 in the folliculus group ; the parietal wall usually bearing a 

 deep-seated entering lamella; columella with one or two cal- 

 lous folds or denticles, tapering but not distinctly truncate 

 at base. 



Chiefly African, only one species being found in Italy, 

 doubtless introduced accidentally. 



The species of Pegea have been chiefly described by Bour- 

 giugnat in his Malacologie de I'Algerie (1864), Prodrome de 

 la Malacologie terrestre et fluviatile de la Tunisie (1887) and 

 various shorter papers. In the work on Tunis a classification 

 of the species into the groups used below is given. Wester- 

 lund, in part III of his Fauna der in der Paldarctischen Re- 

 gion lebenden Binnenconchylien (1887), gives a resume of 

 the species with abbreviated German descriptions. Finally 

 Kobelt has defined and illustrated most of the valid species 

 in an excellent review in his Iconograpkie Land- und Stiss- 

 wasser-Conchylien, new series vol. VII, 1896. 



F. atava Crosse (Journ. de Conchyl. 1862, p. 166, pi. 7, 

 f . 19, 20 ; Coquand, Geol. et Pal. Constantine, p. 312, pi. 29, 

 f. 22, 23) is a fossil species from the Pliocene (?) of Ain-el- 

 Hadj-Baba, near Constantine, Algeria. 



F. arctica Westerlund. A species measuring 7 x 2.75 mm., 

 having the parietal lamella of the subgenus Pegia, believed to 

 have been collected by Charles Rabot in Russian Lapland at 

 Kitza, on the Kola peninsula. The occurrence of a larnellose 

 Ferussacia in this frigid region is remarkable, and requires 

 confirmation. (Ferussacia arctica WESTERL., Comptes Ren- 

 dus de 1'Acad. des Sci., Paris, vol. 108, 1889, p. 1315, foot- 

 note; Nachrbl. d. M'alak. Ges. 1889, p. 169). 



Group of F. splendens (Phylacus Westerlund). 

 Species having the appearance of the F. folliculus group, 

 but with a parietal lamella and columellar margin similar 

 to the species of Pegea. 



22. F. SPLENDENS Bourguiguat. 



Shell relatively quite short, but still oblong, sub vent ri cose, 



