ALARIA. 119 
that Phillips’ figure may have been meant for this one; for, although figured in 
the plate showing the Scarborough-Limestone fossils it has somewhat the look 
of a Dogger specimen. 
Description : 
Length : : . 26mm. 
Width of body-whorl ie length of Shell . - 3o8:100 
Approximate spiral angle : « 3 
The spire is mainly on the type of Alaria heii but there is considerable 
variation in the several specimens; the whorls are more angular in some (fig. 13 a, 
fig. 13 c), more rounded in others (fig. 13 5) ; the position of the keel in the whorls of 
the spire also varies, being central in figs. 13 a and 13 d, and situate in the posterior 
third in fig. 13 c. The longitudinal coste likewise show considerable difference. Part 
of this apparent difference is due to mal-preservation (fig. 13 a). The body-whorl 
is without coste, and the anterior keel is so much aborted that the species is 
practically unicarinate. The keel gives birth to a very large spine a quarter of a 
turn above the base of the wing, and to another spine a quarter of a turn farther 
back, the latter being exactly opposite the wing. 
The aperture is triangular, the wing being pretty full for a Monodactyl, and 
terminating in a stout digitation, the exact nature of which has not been ascer- 
tained. Canal straight at first, but the exact termination unknown. 
Relations and Distribution.—The affinities of Al. wnicarinata have already been 
partially indicated; when mere fragments of the spire alone are preserved, as is 
too often the case, it cannot well be distinguished from the mass of costated and 
turrited Alarie. Not uncommon in the Yorkshire Dogger; it probably occurs in 
the Duston ironstone. 
N.B.—It should be observed that fig. 13 a is not a back view, but just midway 
between a back view and a front view. The fracture on the keel represents the 
posterior spine broken off ; the anterior spine is seen on the left. 
39. Atarta unicornis, Lycett, 1853. Plate V, fig. 1. 
1853. RosreLLaRta untcornis, Lycett. Proc. Cotteswold Nat. Field Club, vol. i, 
p- 80. 
Description.—* Spire lengthened, composed of many whorls; whorls cos- 
tated, the coste terminating in knobs on their upper portions; coste ten in a 
volution, indented by five encircling striz, last whorl smooth with a single prominent 
carina, having an acute and elevated spine about a quarter the circumference poste- 
riorly from the outer lip; the wing single, rounded, curved, slender, and produced ; 
caudal extremity moderately long.” —Lycrrt. 
