ALARIA. 127 



Relations and Distribution. — Whether this curious species is a Monodactyl or 

 an Adactyl cannot at present be decided. The condition of the available specimens 

 is such as to lead to very grave suspicions. It is probably related to Al. Lotharingica. 



Very rare in the Murchisona-zone of Halfway House. 



We may fairly refer to these narrow-angled and elongate Alarias as the 

 Lotharingica-growp ; and with this group terminates Section I, or the Monodactyls 

 in the wider acceptation of the term. 



Division II. The Didactyls. 

 Section 1. — Imperfectly Didactyl. 



49. Alaeia Doublieri, D'Orbigny. Plate V, fig. 11 ; Plate VI, figs la, lb, 1 c. 



1850. Pteeoceba Doublieei, D'Orbigny. Prod, i, p. 270. 



1866. Alabia — — Piette, Cont. de la Pal. Franc?., p. 54, 



pi. vi, fig. 1 ; pi. vii, fig. 1. 



Bibliography, 8fc. — D'Orbigny observes that this species is near to Pterocera 

 (Chenopus) Philippi, K. and D., referred to by Piette as Maria bicarinata. The 

 type is said to have been derived from the Department of the Var. The specimens 

 described and figured by Piette were so imperfect as to leave his determinations 

 somewhat incomplete. But the semi-digitation, so to say, of the anterior portion 

 of the wing, in addition to a considerable resemblance in the spire, helps to connect 

 D'Orbigny's species with certain specimens found in the Inferior Oolite of Dorset- 

 shire, which can scarcely all be referred to one species. These, however, for the 

 present may be treated as varieties. 



Var. A. (Plate VI, figs, la, lb, la). 



Hon. — Length of a full-grown specimen about 30 mm. ; approximate 

 spiral angle 36.° Shell conoidal, fusiform, apex of spire very blunt. Number of 

 whorls about ten. The first five or six whorls 1 are convex and nearly smooth, or 

 only marked by fine spiral lines ; next succeeds a whorl with fine spiral lines and a 

 faint submedian keel. The three remaining whorls of the spire, in addition to the 

 fine spiral lines, develop a strong and rather blunt median keel, which at once 



1 None of the available specimens of this variety exhibit the extreme apicals in such a condition 

 as to afford the means for a thoroughly accurate description. 



