194 W. H. Hudleston — On the Yorkshire Oolites. 



state of conservation is such that no closer description can be given : 

 it is difficult to say how far the smooth appearance of the spire is to 

 be relied upon as a character. 



The specimen is unique, and was found by the late Peter Cullen. 

 It has been suggested that the shell might be that of a Pteroceras. 



Genus Purpttkina, D'Orbigny, 1847, Prod. i. p. 270. 



Defined by Deslongchamps, 1860 (Bull. Soc. Linn. Norm. vol. v. 

 p. 136). 



The history of Purpurina is rather singular. D'Orbigny gives 

 a short diagnosis in the Prodrome, and names several species from 

 the Bajocian, Bathonian, Callovian, and Oxfordian; all of which, 

 perhaps, belong to the genera Brachytrema and Purpuroidea of 

 Lycett. In the "Terrains Jurassiques," as is well pointed out by 

 Deslongchamps,^ numerous figures of Purpurina are given in the 

 atlas, most of which belong to the genus Eucyclus (Amberleya). In 

 the text D'Orbigny says nothing about the genus Purpurina, nor is 

 there a word of description of any of the species figured. 



It is clear that the able author of the Paleontologie Fran^aise 

 abandoned his offspring in the most heartless manner. Fortunately 

 there is just one figure of a most characteristic form, P. bellona, 

 D'Orb. (T. J. pi. 331, figs. 1 and 3),^ from the Inferior Oolite of 

 Bayeux, and this has been accepted both by Piette (Bull. Soc. Geol. 

 de la France, 2'^'^ series, vol. xviii. p. 587) and by Deslongchamps 

 for the type of a genus, which, as defined by them, has relations on 

 one side with Turbo, and on the other with Cerithium and Purpura. 



'•'These shells," says Deslongchamps (vol. ci'i. p. 176; p. 24 of 

 the separate Memoir on the Fossils of Montreuil-Bellay), "are 

 characterized by a thick test, a small groove more or less pronounced 

 in front of the mouth, especially in early life, by an umbilical slit of 

 very limited extent, by the whorls of the spire presenting longi- 

 tudinal ^ ribs more or less marked, cut by transverse stri^, a strong 

 keel, or at least a very pronounced 'ressaut,' forming upon the 

 whorl a ' meplat ' towards the suture, which is deeply cut : finally 

 a body-whorl much more developed than the others." These features 

 are not in every case to be made out, owing to the conditions of 

 preservation. 



In the Inferior Oolite of Dundry * the genus is fairly represented, 

 and it occurs sparingly in the Grreat Oolite, Cornbrash and Kello- 

 way Eock, above which latter I cannot trace it in England. The 



1 op. cit. p. 140. 



2 To complicate matters still more, the type species is not enumerated in the 

 Prodrome list as a Purpurina, but as a Turbo, "munie de fortes ondulations longi- 

 tudinales, et de nombreuses cotes transverses. France, Bayeux (Calvados)." As if 

 this was not enough, we have also (Prod. i. p. 299) Trochus bellona. This is quite 

 a different thing ; it is referred to in the text of the T. J. p. 284, and figured, pi. 

 316 — -figs. 1-4 — whilst Turbo bellona, the future type of the genus Purpurina, is 

 omitted altogether from the text. 



3 Deslongchamps here uses the word longitudinal in a sense which some would call 

 transi'erse. 



* Cf. Tawney, Dundry Gasteropoda, p. 3 of separate Memoir. 



