VOL. XVII. (2) JURASSIC GERVILLI^ 237 



NOTES ON SOME SPECIES OF GERVILLIA FROM 



THE LOWER AND MIDDLE JURASSIC ROCKS 



OF GLOUCESTERSHIRE' 



By E. TALBOT PARIS, P.C.S. 



[Plates XXVIII.-XXIX.] 



I. INTRODUCTION 



During the progress of my work in connection with the 

 revision of the lamelUbranchs from the Lower and Middle 

 Jurassic rocks^ of Gloucestershire, a considerable amount of 

 useful information concerning certain species of the Genus 

 Gervillia has been obtained, which it appears desirable to 

 record in the Proceedings of the Club. 



All the specimens referred to in this paper are in Mr 

 Richardson's collection, unless otherwise stated. His collec- 

 tion has been mainly studied because it appeared desirable to 

 be sure of the horizons from which the specimens were obtained. 



The Genus Gervillia belongs to the family Pernidae, Zittel. 

 The Pernidse altogether embrace seven genera. Of these, one 

 {Bakewellia) is found only in Permian deposits, another {Odon- 

 toperna) occurs only in the Trias, and another (Crenatula) does 

 not definitely make its appearance until the Cretaceous period. 

 The remaining four (Gervillia, Perna, Pernostrea and Inocera- 

 mus) are known to occur in Jurassic rocks, but the Lower and 

 Middle Jurassic rocks of Gloucestershire have yielded represen- 

 tatives of only three, namely, Gervillia, Perna and Inoceramus. 



I I have to acknowledge my indebtedness to the Government Grant Committee of the Royal 

 Society for assistance towards acquiring the information contained in this paper and figuring the speci- 

 mens. 



2 As defined by Mr A. J. Jukes-Browne in "The Students' Handbook of Stratigraphic.->1 

 Geology." 



R 



