18 MOLLUSCA FROM THE GREAT OOLITE. 



fold or varix, of which there are two upon the last volution. The inner lip is broad and 

 distinct, the channel is short and straight. A small canal passes from the aperture to the 

 apex of the rudimentary digitation. 



M. Deslongchamps has described this species from three small specimens, which are 

 very imperfect, having only the last volution. The name is scarcely appropriate to full- 

 grown individuals which nearly lose the hook-like digitation ; in one instance only have 

 we noticed the hamulus of the dimensions figured by M. Deslongchamps, and this occurred 

 in the smallest of our specimens, which was but little larger than the Norman one. It 

 would, therefore, seem that this feature was of an uncertain character, and disappeared at a 

 later period of growth. 



Locality. The beds of planking at Minchinhampton Common, and their equivalents, 

 the white stone of Bussage and Eastcombs, have supplied all the specimens which have 

 come to our knowledge. It is not very rare. In the Great Oolite (pierre blanche), 

 Langrune, Normandy. {Desl.) 



Alaria Phillipsii, lyOrb. sp. Plate III, figs. 5, ha. 



Pterocera Phillipsii, If Orb. 1850. Prod. Paleout, p. 2/0. 



Rostellaria composita, Phil. 1835. Geol. Yorksh., i, t. 9, fig 28, (not Sow.) 



A. Testa turritd ; spird elongald; anfractibus numerosis, converts, vel subangulatis, 

 transverse striatis, et costis obliquis numerosis approximatis ; anfractu ultimo bicarinato ; 

 old unidigito, caudd recta, breviusculd. 



Shell turrited; spire elongated; whorls numerous, convex, or subangulated, trans- 

 versely striated, and ornamented with numerous closely-arranged oblique ribs upon the 

 lower half of each whorl ; the last whorl is striated and bicarinated, terminating in a simple 

 or undivided wing ; the caudal extremity is straight, smooth, and of moderate length. 

 A. hamus is the species which approximates most nearly to it; but in that shell the 

 longitudinal costae are less numerous, not oblique, and are visible throughout the length of 

 the whorl ; whereas in the A. Phillipsii they occupy the lower half only, and form an angle 

 at their upper termination. The upper and larger carina upon the last whorl is more 

 smooth and less prominent than in the A. hamus, and the entire form of the shell more 

 lengthened or slender. 



Locality. Scarborough, in dark chocolate-coloured argillaceous shale. Great Oolite, 

 {Phillips.) 



Alaria pagoda. Plate III, fig. 6. 



Testa turritd; anfractibus numerosis, in medio carinato-crenatis, ultimo bicarinato; 

 carinis tuberculatis ; anfractibus transverse striatis ; striis duabus prominentibus suturam 



