G4 FAUNA OF THE CORNBRASH. 



Ala via not actually showing the digitations of the wings, and with whorls striated 

 and keeled may represent this, such as A. cornuta (of Piette or A. jmhjgona). It 

 seems very probable that the second species figured by Phillips, as B. bispinosa, 

 from the Kelloway rock (lor. cit., pi. vi, fig. 13) is the same as this. For the 

 long digitations might easily be found to be hidden in the matrix if the specimen 

 were at hand, but the name assigned belongs to the other species (so called) and 

 cannot be used for this. The horizon, however, seems doubtful, it having been 

 referred in the third edition to the Cornbrash, and called A. myuvus, which it 

 obviously is not. 



(c) Spire with longitudinal ribs (Hamus group). 

 Alaria composita (Sowerby). Plate VII, figs. 7, 8. 



1827. Rostellaria composita, J. de C. Sowerby, Min. Conch., p. Ill, pi. dlviii, fig. 2. 



Tijpe. — Shell turreted, striated, with costated spire. Last whorl armed by two 

 keels, one lobe only cuspidated on the outer lip. From the Oxford Clay of 

 Weymouth and Brora. 



Description. — The specimen here referred to this species is of larger size than 

 the type, but that is about the only difference. Four whorls before the last are 

 preserved, and there were probably at least three more. The spiral angle is 26°. 

 The lower half of all the whorls except the last is crossed by about 12 longi- 

 tudinal ribs, which are low anteriorly, but swell out to a maximum in the centre 

 of the whorl and then die out suddenly, especially in the later whorls. In the last 

 whorl they are confined to the keel itself, which they swell out and render gibbous, 

 but this gibbosity is lost as the aperture is approached. The lower keel has a 

 similar gibbosity in the same way and near the same place, but dies out almost 

 to nothing at the edge of the wing. The whole of the surface is covered with 

 irregular spiral riblets, continuing below the anterior keel as far as the shell is 

 preserved ; and crossing the ribs in the spire over all are fine sigmoid lines of 

 growth. The penultimate whorl is very angular in outline, and the wing extends 

 back upon it a little beyond the line of knobs. The upper digitation or outer 

 process is very short and curved upwards (i.e. backwards). The lower keel 

 having died away, the anterior edge of the wing is carried by a gentle curve to 

 the point where the canal sheath is broken off. Where the shell is broken off the 

 cast is seen to show only a gentle spiral swelling (the shell being thick) and to 

 become attenuated at the apex. The aperture in this specimen shows the thin 

 left lip spread over the penultimate whorl. 



Distribution and Relations. — The above shell is from Scarborough, in a truly 



