J. Starkie Gardner — On the Gault Aporrhdidw. 125 



The specimen labelled A. retusa, from Devizes, in the Jermyn 

 Street Museum, has an expanded wing, and is more elongated an- 

 teriorly than A. retusa from Folkestone. 



Addendum to Group 2. 

 There are two specimens from the Upper Greensand of Evershot 

 of a large Aporrhais, allied to A. cingulata, in the collection of the 

 Geological Museum, Jermyn Street. I shall take a future opportunity 

 of describing them. Meanwhile, as they are perfectly distinct from 

 any other Continental or British form, I propose to name them 

 Aporrhais Etheridgii, in compliment to Mr. Etheridge, F.R.S., 

 Palaeontologist to the Geological Survey of Great Britain. 



Erratum in last Number : p. 53, line 13, read, except from Aachen. 



Group 3. — Spire long, whorls angulated, carinated or bicarinated, 

 spirally striated, generally with nodes or ribs transverse to the 

 whorls ; wing narrow and long, simple or bifurcated. No posterior 

 canal. 



Type : — Aporrhais carinata, Mantell (1822). Plate V. Eig. 1. 



Description. — Spire elongated, composed of about 12 convex 

 angulated whorls, forming an angle of 21° ; finely striated spirally, 

 ornamented transversely on the convexity of the whorls by 10 or 11 

 salient, slightly oblique and generally elongated tubercles. The 

 sutures are very visible and slightly keeled. Fainter and less regular 

 striae cross the spiral lines, and coincide in direction with the ribs ; 

 they are especially visible on the sutural keels. The tubercles en- 

 tirely disappear on the last whorl, and are replaced by two very 

 salient angular striated keels, the posterior of which is most prominent 

 and is prolonged to the extremity of the wing, in the form of a very 

 strong, narrow, rounded ridge ; this ridge or wing process runs at 

 first at right angles to the axis, and then abruptly curves upward 

 and continues more or less parallel to the spire, which it equals or 

 even exceeds in length ; it terminates in a sharp point or canali- 

 culated spine. A second anterior keel rises in most specimens, if not 

 all, near the margin of the lip, runs parallel to the first for a short 

 distance, and at the point of curvature, diverges in an opposite and 

 slightly outward direction in the form of a comparatively short and 

 sharp, solid spur ; the space between the two keels forms a narrow 

 triangular wing, truncated at its extremity. The wing is applied to 

 the last, and sometimes very slightly to the penultimate whorl ; 

 although slender looking and elegant, it is remarkably thick and 

 strong. The spire measures -046, canal -036 ; breadth, including 

 wing, '036; the length of posterior digit from the point of curvature 

 is -034, and of the anterior digit -012. The outer lip between the 

 wing and anterior canal is slightly sinuous ; the anterior canal equals 

 the length of the spire, is slender, and is either straight or curved to 

 the right. Mouth narrow, columellar lip encrusted immediately 

 round the aperture. A slight modification of this species occurs in 

 the Upper Gault, in which the posterior digit of the wing is shorter, 

 straighter, and diverges outwards; the anterior spur is longer in 



