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 Murchisone-zone of Halfway House. 
We may fairly refer to these narrow-angled and elongate Alarias as the 
Lotharingica-group ; and with this group terminates Section I, or the Monodactyls 
in the wider acceptation of the term. 
Division II. Tue Dipactyts. 
Sxotton 1.—Imperfectly Didactyl. 
49, Avarta Doosuieri, D’Orbigny. Plate V, fig. 11; Plate VI, figs la, 1b, le. 
1850. Prrrocera Dousiiert, D’Orbigny. Prod. i, p. 270. 
1866. ALARIA _ — Piette, Cont. de la Pal. Frang., p. 54, 
pl. vi, fig. 1; pl. vii, fig. 1. 
Bibliography, §c.—D’Orbigny observes that this species is near to Pterocera 
(Chenopus) Philippi, K. and D., referred to by Piette as Alaria 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. ‘hese, however, for the 
present may be treated as varieties. 
Vaz. A. (Plate VI, figs. 1a, 1b, 1 ¢). 
Description.—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! 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. 
