292 ./. Starkie Gardner — On the Gault Aporrhdidce. 



this and the penultimate whorl a subordinate keel appears between 

 the two principal ones ; the body-whorl is ornamented in addition 

 by spiral stria? arranged 1 above, 3 between, and 6 below the carina? 

 — a sutural keel also becomes visible. 



The wing, which is exceedingly expanded, is supported by 3 strong 

 ridges or spines, 2 of the spines being prolongations of the carina? 

 mentioned above, and the third taking the place of the anterior canal. 

 There were also two intermediate spines rising from the margin of the 

 wing and dying away before reaching the body of the shell, only 

 one of these remains on the figured specimen. The wing had thus 

 five points. The middle spine is unfortunately broken away, but 

 there is no doubt that it was present on the shell. The anterior 

 spine or canal is curved backward, and there is a curious and un- 

 usual triangulariform expansion to the left of the canal. 



After careful examination under the microscope, the slightest trace 

 only (and I am most doubtful whether it really is a trace) of at- 

 tachment of the wing to the spire is apparent, and I am now inclined 

 to think that the wing expansion did not extend up the spire, but 

 that its upper termination shown in the figure is the actual posterior 

 margin of the pterygoid process. 



History. — Sowerby figured this shell in the Geol. Trans., 2nd 

 series, vol. iv. pi. xviii. fig 23. No second specimen I believe has 

 been found. The fossil figured by Briar t and Cornet as this species 

 in no way resembles it. 



Locality. — Blackdown. 



I am indebted to the courtesy of Mr. E. B. Tawney for the op- 

 portunity of examining this unique shell, as well as the original 

 specimen of A. retusa, figui-ed by Sowerby on the same plate. I 

 may here state that this latter is identical with the Folkestone and 

 Lyine Kegis shells. 



Since writing these notes on Aporrhai'da?, I have had an oppor- 

 tunity of examining the Neocomian forms, descriptions of which, 

 together with those of a few species formerly unknown to me, will 

 be found in the following supplement. 



Supplement. 



Group 1 (see p. 52). PI. VII. Fig. 3. 



Aporrha'i's Moeeausiana, D'Orb. 



Description. — Shell thinner and more elongated than that of A. 

 Fittoni, and less delicate than A. retusa, the spire being composed of 

 5 or 6 whorls, ribbed spirally and forming a slightly convex angle. 



As in most species of this group, the last whorl only is seen to be 

 bicarinated, the anterior keel being hidden by the suture in the re- 

 mainder: The whorls composing the spire are very angular, much 

 more so than in A. Fittoni. On the last whorl there are at least 2, 

 generally 3 spiral stria? between the keels, 3 stria? above the posterior 

 keel, and 4 or 5 below the anterior keel. The two keels are not 

 very prominent, and are somewhat rounded, the posterior one pre- 

 dominates, and is slightly tuberculated. The keels are continued 



