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 . . . . .26 mm. 



Width of body-whorl to length of shell . . 38 : 100 



Approximate spiral angle . . . 31° 



The spire is mainly on the type of Maria hamus, 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 b) ; the position of the keel in the whorls of 

 the spire also varies, being central in figs. 13 a and 13 b, and situate in the posterior 

 third in fig. 13 c. The longitudinal costse likewise show considerable difference. Part 

 of this apparent difference is due to mal-preservation (fig. 13 a). The body-whorl 

 is without costse, 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 AX. unicarinata 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 Ala/rice. 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. Alaria unicornis, Lycett, 1853. Plate V, fig. 1. 



1853. Kostellahia unicornis, Lycett. Proc. Cotteswold Nat. Field Club, vol. i, 



p. 80. 



Description. — " Spire lengthened, composed of many whorls ; whorls cos- 

 tated, the costse terminating in knobs on their upper portions ; costse ten in a 

 volution, indented by five encircling striae, 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." — Lycett. 



