JDr. John Lycett—Note on Purpuroid Shells. 499 



figured in 1827 from tlie Pisolite of Malton, a specimen so imperfect 

 that it was stated by Mr. Sowerby to be but little better than a cast, 

 and accordingly he did not venture to determine the genus with 

 any certainty. I had, however, a conviction that Sowerby's shell 

 (tab. 578) was identical generically, and perhaps as a species also, 

 with the Murex nodiilatus of Young and Bird, whose figure in the 

 first edition of their work (1822) was assigned to the genus 

 Buccinum. My description of the genus Purpiiroidea, given in the 

 Annals and Magazine of Natural History in 1848, was perfectlj^ 

 correct in definition, but had one disadvantage, that it did not 

 include a close comparison of all the features which separate it 

 from the living and Tertiary I'tirpurce ; at the period in question it was 

 impossible to prove that all the species of Purpuroidea, represented 

 by the few and for the most part imperfectly developed fossils then 

 known, were destitute of an important generic feature possessed 

 by Purpura, which I will now allude to. The shells of Purpura, both 

 living and Tertiary, have a posterior respiratory excurrent or anal 

 canal, forming an internal groove at the posteal junction of the 

 outer lip with the columella; the groove is always well defined, 

 and in none more clearly than in the little Purpura lapillus so 

 common upon our coasts. Tlie shells of tlie Jurassic Purpuroidea are 

 all destitute of this feature, which is possessed also by some other 

 recent genera of the Siphonostomata. 



In 1852 appeared the splendid Atlas of Buvignier illustrating the 

 Jurassic fossils of the Meuse, and containing finely executed figures 

 of the three Purpiirce previously figured by him, and fully proving 

 their distinctness from the G-reat Oolite species of England. Several 

 years subsequently M. E. Piette described and figured three other 

 species of our genus from the Great Oolite of the Ardennes and 

 I'Aisne, Bull. Soc. Geol. France, tom. 13, pi. 12, 13, 14, pp. 290, 

 296 ; these also were all assigned to the recent genus Pupura, and 

 one of them to the Gloucestershire Great Oolite species P. glabra. 

 This I believe to be an erroneous identification. To these must now 

 be added the figures of two species of Purpuroidea b}' Mr. Hudleston, 

 occupying Plate VIII. in this Magazine for 1880. There are there- 

 fore now known, described, and figured, six species of Purpuroidea 

 in the Great Oolite, three in England and three in France; five 

 species in the Corallian rocks, three in France, and two in England, 

 to which may be added not less than two other species hitherto 

 undesci'ibed, but noticed by Mr. Hudleston, one in the Coral Eag 

 of Yorkshire, and a small one in the Portland formation in the 

 limestone of Portland ; the eleven species already described , are 

 believed to be all separate forms. In mentioning three Great Oolite 

 British species, I purposely omit the Purpuroidea insignis, Lye, 

 figured and described from a single specimen in my supplement to 

 the Great Oolite, Monograph, p. 6, pi. 31, figs. 2, 2a, as I am now 

 convinced that the specimen upon which that species was founded 

 possesses only individual peculiarities common to an exceedingly 

 variable form, one of which is not unfairly represented by the 

 woodcut given in the Annals in 1848 above alluded to. 



