54 /. Starkie Gm % dner — On the Gault AporrhaidcB. 



P. bicarinata, which he says he had never seen, but giving them both 

 from the Gault of Folkestone, where certainly only one species is found. 

 Mr. Tate describes P. bicarinata as follows : — " Possesses two keels, 

 each corresponding to a long digitation, an anterior canal, and a 

 posterior expansion towards the spire." This description applies 

 equally to A. retusa, in fact the two names are synomyms for the 

 same species. In 1869 Jaccard cites it from the Lower Gault of 

 Ste. -Croix. 



Other species belonging to this group. 



P. Moreausiana, D'Orb. Lower Greensand. 



P. Fittoni, Forbes. Probably synonymous with above. Lower 

 Greensand. 



P. globulala, Seeley, 1861, Greensand, Cambridge, appears to 

 differ only in size. 



A. bicornis, P. and C, from the Upper Gault, very closely resembles 

 . retusa, but seems to have had a rather longer spire. 



P. macrostoma, Briart and Cornet, is a similar form with dilated 

 lip ; quite distinct from the B. macrostoma, Sow. 



B. ovata, Minister, Green Chalk of Haldem, bears considerable 

 resemblance in form, but the figure in -Goldfuss, Petr. Germ., shows 

 a pointed spine in the middle of second whorl, as in Oolitic A. 

 spinigera. 



Ghenopus Gouloni, de Loriol, 1861. No keels, except two on body- 

 whorl, spire longer than P. Moreausiana. Neocomien of Mont- 

 Saleve. 



Two undescribed species from the Grey Chalk of Dover. 



Group 2. — Shell pupseform, with keels prolonged in two very 

 long narrow flexuous digits, anterior canal long and resembling the 



digits. 



Type: — Aporrha'i's cingulata, Pictet and Eoux. PI. III. Figs. 7-10. 



Description. — Shell elongated and pupasform, composed of about 

 eight convex inflated whorls, the last of which is smaller than is 

 required to form a regular cone, being but one-sixth more in 

 diameter than the preceding whorl. "Whorls with four simple longi- 

 tudinal salient but rounded keels, without trace of tubercles. On 

 all but the last, the two median keels are equally prominent ; of the 

 other two, the anterior is very small, and is nearly concealed by the 

 suture ; the posterior is more or less subordinate to the two median 

 keels, and is situated midway between them and the suture, its 

 relative prominence being very variable. On the last whorl the 

 posterior median keel is much more pronounced than the other, and 

 is prolonged into an exceedingly long narrow flexuous digit, which 

 is convoluted, taking a half turn near the lip, and then curving 

 gradually upwards, attaining a length exceeding twice that of the spire. 

 The process is grooved underneath. The anterior keel forms another 

 downward spiked digit not convoluted, and of less length. The 

 anterior canal is about one and a half times the length of the spire, 

 is flexuous, and generally abruptly recurved, or bent backwards at 



