110 GASTEROPODA OF THE INFERIOR OOLITE. 
Division I. Tur Monopacryts. 
27. ALARIA ARENOSA, Hudleston, 1884. Plate IV, fig. 1. 
1884. Ataria arENosa, Hudl. Geol. Mag., dee. iii, vol. i, p. 198 (May), pl. vii, 
fig. 7. 
Description : 
Length’. : . 20 mm. 
Width of hodyswhorl't to length of Shell . rel 10: 
Approximate spiral angle : ee 
Shell fusiform, turrited. Number of whorls soot ten, apical ones unknown. 
Each whorl has a median carina which is strongly tuberculated. In the upper 
whorls this tuberculation is extended axially so as almost to reach from suture 
to suture; but in the last two whorls it is confined to the region of the keels. 
The whorls are marked with rather strong spiral lines. The body-whorl carries 
two keels ; the upper one is the strongest, and has tubercles very similar to those 
on the penult ; the tuberculations of the lower keel are less strong. The nature 
of the wing is uncertain, there being no outer lip preserved. 
Aperture ?; canal long and moderately curved. 
Relations and Distribution.—Some of the peculiarities of the figured specimen 
are partly due to matrix and condition of the fossil. Piette (op. cit., p. 23) 
alludes to a variety of Rostellaria subpunctata, Mimst., figured by Terquem, which, 
as regards the tuberculations of the lower whorls, may have some resemblance. 
This was from the Opalinus-zone. From Al. Phillipsii this species differs in the 
position of the longitudinal costulz, in the tuberculated keels of the body-whorl, 
and in the slightly narrower spiral angle. 
Rare in the Dogger Sands (Opalinus-zone) this species is interesting as the 
earliest example of Alaria at present known from the Jurassic beds of Yorkshire. 
1 These measurements exclude the canal. Since all Alarie possess a more or less blunt apex, 
with great convexity of the opening of the spiral angle, the “approximate spiral angle” of this and 
subsequent measurements is intended to denote the mean angle of the spire without reference to 
the apical whorls. 
