126 GASTEROPODA OF THE INFERIOR OOLITE. 
Description : 
Probable length . - 40 mm. 
Width of last whorl to jeneth of shell 5 Bey IIL). 
Spiral angle F 5 ale. 
Shell extremely elongate, aneten, turrited. Ahora about ten (six visible in 
the figured specimen), convex, and scarcely angular, since the very slight keel or 
shoulder is close to the anterior suture. The longitudinals consist of regular and 
very straight ribs of considerable thickness, extending nearly from suture to 
suture ; these decussate with a system of rather prominent spirals, which are con- 
tinued in the base of the shell. The body-whorl shows a slight increase beyond 
the regular spiral angle, owing to the development of a strong median keel. 
Piette observes that this keel, which becomes spinous on the side opposite the 
wing, forms in its prolongation a thick digitation bent upon itself, which twists 
towards the point of the spire. 
Relations and Distribution.—This is a Monodactyl of peculiar form, which seems 
almost to stand by itself, or at least to have no near relations, except perhaps in 
some degree to the species next described. Piette describes several varieties. 
It is said to be common in the zones of Am. Sowerbyi and Am. Murchisone, in 
the Department of the Meurthe. The Dundry specimen now figured, originally 
described by Tawney, is at present unique as a British example of this species. 
48. ALARIA PRELONGA, sp.nov. Plate V, fig. 10. 
Description : 
Probable length . . 46 mm, 
Width of body-whorl to feces of pel . 30: 100. 
Spiral angle : see ie 
Shell extremely elongate, fed Whorls ten or eleven in number, and 
moderately angular, the keel being situate rather more than one-third the distance 
from the anterior suture. The longitudinals are mainly confined to the anterior 
area of the whorls, and consist of very straight stout costz, decussating with 
spirals which are more or less obliterated in the available specimens. In the 
penultimate the longitudinals fail entirely, the keel being plain and nearly median. 
There is a sharp rise of the keel in the body-whorl, which keel is also plain with 
indications of a spinous projection on the side opposite the outer hip ; the position 
of the keel is irregular. 
The aperture is triangular, and there is a considerable callous deposit on the 
columellar side. The indications of a wing and canal are not distinct. 
