118 GASTEROPODA 0¥ THE INFERIOR OOLITE. 



37. Alabia : Cf. rarispina, ScMumberger, 1864. Plate IV, fig. 12. 



1864. Ar.AHiA RARispiNi., Schlumberger. Bull. Soc. Linn. Norm., vol. ix, p. 225, 



pi. vi, figs. 7 — 9. 



1867. — — — Piette, Continuat. Pal. Franc., p. 100, 



pi. xx, figs. 1—3. 



This specimen sufficiently resembles the description given by Piette to warrant 

 its comparison. The spire has an angle of about 26° ; whorls angular, keel about one 

 third distant from the posterior suture ; costas very wide apart, but extending almost 

 from suture to suture ; spirals fine and wavy. Part of the penultimate is devoid of 

 costaa. 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 Soiverbyi-Murchisonce- 

 zone of the Meurthe. 



The specimen here figured is probably from the Sowerbyi-hed 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. unicarinata, Al. unicornis, and Al. unicornis, 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 unicarinata, Hudleston, 1884. Plate IV, figs. 13 a, 13 b, 13 c. 



1881. Alabia unicaeinata, Hudl. Geol. Mag., dec. iii, vol. i, p. 149, pi. vi, 



figs. 1, 2, 2 a. 



Bibliography, Sfc. — 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 



