J. Starkie Gardner— On the Gault Aporrhdida. 53 



dilated, forming a palmate expansion, uniting the digits for part of 

 their length (see Fig. 3). The mouth is narrow, oblique and oblong. 

 The spire measures without canal -016; canal alone -025; digits 

 •030. 



Distribution.— This is a most widely distributed form, being found 

 abundantly at Folkestone, Lyme Eegis, and at Cambridge, 1 Black- 

 down and Devizes, Eingmer, 3 etc. I have seen no specimens except 

 from Folkestone and Lyme Begis. The same, or an allied form, is 

 found in the Aptien beds of Folkestone. Morris gives it from Ather- 

 field, but this is no doubt an error. 



On the Continent it has been found throughout the Paris basin, 

 Doube, Varennes, Ervy, Saxonnet, Perte-du-Ehone, Sainte-Croix, 

 but I have not seen it described from Aachen in German works. 



History. — First described in 1836 as Bostellaria retusa by J. 

 Sowerby, in Fitton, Geol. Soc. Trans., vol. iv. p. 344, pi. 18, fig. 22. 

 I cannot find the type or any specimen from Blackdown, and there is 

 a doubt whether the same species is intended. Sowerby says, "It 

 has only one elongated narrow branch to the lip. The surface 

 between the stria? is particularly smooth." Should the Blackdown 

 form prove distinct, Deshayes' name of hicarinata must be adopted 

 for it, 



Leymerie, in 1842, in the Mem. Soc. Geol., figured a young spe- 

 cimen as B. hicarinata, and noticed the more delicate ornamentation, 

 "spire delicately ' quadrillee' by the intersection of fine transverse 

 ribs and of slightly oblique longitudinal striae." In the same year 

 D'Orbigny figured this species in his Pal. Fr. Terr. Cret., vol. ii. 

 p. 307, pi. 208, figs. 3 and 5, from the Albien of Aube and Ardennes, 

 but in an unsatisfactory manner. He observes, " Young or old, it is 

 clearly characterized from all other forms by its singular shape." 



In 1845 Forbes mentions it in the Quarterly Journal. In 1849 

 Pictet and Eoux figured and described this shell in the Moll. foss. 

 Gres-verts, p. 263, pi. 25, fig. 11, but did not consider it identical 

 with that in Fitton's memoir. Geinitz, in his Quader-sandstein- 

 gebirge, also figures this shell as Strombus (Pterocera) bicarinata, 

 t. ix. fig. 4. The three names in D'Orbigny's Prodrome are 

 probably synonyms for this one species. In 1854 Professor J. 

 Morris, in his catalogue, considers it distinct from P. retusa of 

 Blackdown. The same year Cotteau, and in 1858 Leymerie, mention 

 it from the Yonne. ■ In 1859 Dr. Chenu figured P. bicarinata in the 

 Man, Conch., p. 260. It occurs in Gabb's list of 1861, pp. 56, 71, 

 under Klein's name of Harpago (1753). In 1864 Pictet and Cam- 

 piche and Pictet and Eoux described it. The figures in Pictet and 

 Campiche, pi. xci. figs. 5 to 8, differ, however, from our British form, 

 except fig. 5 ; perhaps owing to their being figured from imperfect 

 specimens. In 1865 Briart and Cornet, Descr. Min. de la Meule 

 de Bracquegnies, p. 17, pi. 2, fig. 3, figure a specimen with dilated 

 lip as P. macrostoma, Sow., a species it in no way resembles, and 

 also figure P. retusa, but with a different form of wing. In the 

 same year Mr. E. Tate described P. retusa, but separated it from 

 1 Seeley. 2 Fitton, Morris, etc. 



