118 GASTEROPODA OF THE INFERIOR OOLITE. 
37. Avarta: Cf. rarispina, Schlumberger, 1864. Plate IV, fig. 12. 
1864. Avarta raRispina, Schlumberger. Bull. Soc. Linn. Norm., vol. ix, p. 225, 
pl. vi, figs. 7—9. 
1867. — — — Piette, Continuat. Pal. Frang., p. 100, 
pl. xx, figs. 1—3. 
This specimen sufficiently resembles the description given by Piette to warrant 
its comparison. The spire hasan angle of about 26°; whorls angular, keel about one 
third distant from the posterior suture ; costz very wide apart, but extending almost 
from suture to suture; spirals fine and wavy. Part of the penultimate is devoid of 
coste. Body-whorl scarcely bicarinate, and showing traces of a varix or spine on 
the keel. 
Piette observes that Schlumberger’s shell is very distinct from all other hami- 
form species; it was described from a single specimen in the Sowerbyi-Murchisone- 
zone of the Meurthe. 
The specimen here figured is probably from the Sowerbyi-bed in Dorsetshire. 
It is certainly a more angular shell than the one figured by Piette, which, as 
regards the spire only, has more resemblance to the form (PI. IV, 3) provisionally 
named “ crassicostata.”’ A specimen lately acquired for the York Museum, in a 
similar matrix, shows that the wing-digitation is more produced and less sharply 
curved than in Al. hamus. Rare. 
The following species, viz. Al. wnicarinata, Al. wnicornis, and Al. wnicornis, var., 
constitute a subgroup related to Al. hamus, but distinguished in possessing a some- 
what different digitation, in the effete character of the anterior keels on the body- 
whorl, and especially in the possession of powerful curved spines on the keel 
instead of mere spinous protuberances. ‘They belong also, as it seems to me, to 
a lower horizon. It may be, indeed, that these are only varieties of one species. 
38, ALARIA UNTOARINATA, Hudleston, 1884. Plate IV, figs. 13 a, 13 6, 13 ¢. 
1884. ALARIA uNIcARINATA, Hudl. Geol. Mag., dec. iii, vol. i, p. 149, pl. vi, 
figs. 1, 2, 2a. 
Bibliography, §c.—Two specimens of Alaria, one in the York Museum, the other 
in the British Museum, seemed to me sufficiently distinct from Al. Phillipsii, as 
recognised by Morris and Lycett, to warrant distinction. Since then I have 
ascertained that this is the more usual form in the Dogger. It is just possible 
