THE 



GEOLOGICAL MAGAZINE. 



NEW SERIES. DECADE III. VOL. IV. 



No. v.— MAY, 1887. 



OI^X<3-Z3^J^IJ J^iaTXGXjES. 



I. — British Liassic Gasteropoda. 



By E. "Wilson, F.G.S. ; Curator of the Bristol Museum. 



fPLATE V.) 



Introduction. 



THE Gasteropoda, next to the Lameilibrancliiate Mollnsca, are the 

 most varied class of organisms found in the Lias. The general 

 elegance of their forms, and the frequent beauty of their ornamenta- 

 tion, make these fossils extremely attractive objects ; whilst their 

 limited vertical range gives them a by no means inconsiderable 

 stratigraphical importance. Notwithstanding these inducements to 

 their study, the Gasteropoda of the Lias have not received, in this 

 country, anything like the amount of attention which has been given 

 to the other leading classes of organisms derived from that formation. 

 On the Continent, on the other hand, considerable progress had been 

 made in the investigation of this interesting group of fossil mollusca 

 more than thirty years ago. The elaborate Memoirs of Miinster (in 

 Goldfuss's "Petrefacta Germanise"), D'Orbigny (in the " Paleonto- 

 logie Frangaise"), Deslongchamps the elder, Dunker and Terquem, 

 Chapuis and Dewalque, furnish the basis of our knowledge of the 

 Gasteropoda of the Lias, whilst in later years Messrs. Eudes 

 Deslongchamps, Stoliczka and Piette, Jules Martin and Dumortier, 

 have each and all contributed a large amount of very valuable 

 information in this department of Palaeontology. The above differ- 

 ence, to our disadvantage, is perhaps to be explained, in part at any 

 rate, by the more localized distribution of Gasteropodous Mollusca in 

 the English Lias, by their prevailing small size, and the comparative 

 rarity of the more conspicuous forms, such as the Pleurotomarite, and 

 finall}'', by their generally more highly mineralized condition, and 

 the consequent greater difficulty there is, in this country, in extracting 

 these fossils in anything like perfect condition.^ During recent 

 years, however, an increasing amount of attention has been given 

 to the palaeontology of the English Lias. In this work a number of 

 earnest students are now actively engaged, chiefly in the Midlands, 

 a district which had previously been greatly neglected, and one of 



^ In the Lias of Luxembourg aud Hettange, several Gasteropods have been found, 

 which are not only perfect in form, but even retain the original colours and markings 

 of the shells. (See Terquem, " Paleontologie de Hettange," Aiem. Soc. Geol. 

 France, 2"<i ser. vol. v. pp. 219-343, pi. xii.-xxvi.) 



DECADE III. VOL. IV. NO. V. 13 



