J. Starkie Gardner — On the Gault Aporrhaidce. 293 



into long curved digitations, the digitations being accompanied for a 

 short distance by expansions of the shell, and being less angular and 

 acute than those of A. retusa. There is a short posterior canal ac- 

 companying and attached to the spire, but I am not fully acquainted 

 with the length and development it attains. The anterior canal is 

 bifurcated near its commencement, and is then abruptly recurved to 

 the left. There is a well-marked sinus between this canal and the 

 anterior digit — another deep round notch between the two digits of 

 the wing. The wing has altogether an angular appearance. This 

 shell is readily distinguished from A. Fittoni, with which it is some- 

 times found associated, by the more elongated and angulated spire, 

 and the number of ribs on the last whorl. 



History. — There is very little doubt that this is the Pt. Moreau- 

 siana of D'Orbigny, Terr. Cret. vol. ii. p. 301, pi. 211. It is the 

 Pt. retusa of Fitton, Quart. Journ. Greol. Soc. vol. iii. from the 

 " Cracker rocks," and it is probably identical with the shell described 

 by Pictet and Campiche in the Terr. Cret. de Ste. -Croix, p. 579, as 

 PL bicarinata, Sowerby. These learned authors noticed the tendency 

 of the posterior carina to predominate, and their figure 7, pi. xci., 

 shows the bifurcation of the anterior canal. The figure of Pt. ma- 

 crostoma, pi. ii. fig. 3, of Briart and Cornet's Meule-de-Bracquegnies 

 may also have been drawn from a fossil of this species. It is the 

 Pt. retusa from Atherfield, of Mantell, Forbes, Morris and other 

 British authors. 



Distribution. — Atherfield (Brit. Museum and Geol. Soc. Museum), 

 and Peasemarsh, near Guildford (in Mr. Meyer's collection). It is 

 not possible for me at present to define its continental range. 



Aporrhais Fittoni, Forbes. PL VII. Fig. 4. 



Description. — Shell rather thick, shaped very like the preceding, 

 the spire being composed of five spirally striated whorls. The 

 penultimate whorl has three keels and several striae visible, which 

 disappear on the upper part of the spire, or, more correctly speaking, 

 are reduced to the same prominence only as the striae ; the upper 

 whorls are inflated and ornamented with five or six equal spiral 

 lines, which are decussated by lines of growth. On the body- whorl 

 the carinas and stria? are much coarser, more prominent, and more 

 rounded than in the last described species. Above the posterior keel 

 there are two faint striaa ; between the keels is a single pronounced 

 riblet ; below the anterior keel, are three strongly-marked striae, and 

 beneath these are one or two more faintly marked lines. The two 

 carinas are more or less, but sometimes very strongly tuberculated, 

 and are continued into strong linear curved digits ; there is also a 

 long and elegant posterior canal attached to and extending far be- 

 yond the spire; it is recurved gracefully to the left. There is an 

 expansion of the shell on the upper side of the posterior digit ac- 

 companying it for a short distance, and terminating abruptly in 

 an angle — a similar expansion occurs on each side of the anterior 

 digit. The anterior canal is long and recurved, and has not been 

 observed ever to become bifurcated. The sinus is well marked. 



