UPPER EOCENE (bARTON AND UPPER BAGSHOT FORMATIONS). 619 



of which 252 were Mollusca. The collection of the Geological Sur- 

 vey, as shown by their catalogue in 1865, comprised 182 species, 

 whilst Morris enumerated 219. Prof. Judd, when writing of " the 

 richly fossiliferous marine deposits of the Barton Clay at the base of 

 the Fluvio-marine series " remarks (Q. J. G. S. vol. xxxvi. p. 151) : — 

 *' So long ago as 1857 Prof. Prestwich was able to enumerate no less 

 than 300 species of Mollusca from this formation ; and when all the 

 known forms contained in the numerous collections in this country 

 come to be described, the number of species from this deposit will 

 probably exceed 1000." A somewhat critical examination of the 

 Edwards collection shows about 527 varieties of Mollusca from the 

 Barton Beds entitled to specific rank, and we are not of opinion that 

 this number will ever be greatly exceeded. Fossils belonging to 

 other groups bring the fauna to a possible total of 600. 



The original basis of the tabulated list appended is the catalogue 

 of the Edwards collection in the British Museum. To this we have 

 added as much as possible on the one hand, whilst removing on the 

 other all forms of doubtful specific value. In tabulating the range 

 of the species, we have endeavoured to distinguish their occurrence 

 in each division of the Barton Series ; and we believe that the long 

 residence of one and the repeated visits of two of us to the locality, 

 for the purpose of collecting, enable us to deal with the question of 

 the horizons to which species are confined, with a practical expe- 

 rience that it is scarcely probable any other workers have exceeded. 

 Many, especially of the minuter forms identified by Edwards, are 

 almost, if not quite, unique, and we have no means of ascertaining 

 their horizons with certainty. We regard the record of some of the 

 Barton species from other formations as doubtful, but do not sup- 

 press them, as we have ourselves discovered several fresh Barton 

 species in Bracklesham Beds whilst preparing this paper. "We 

 endeavour to obviate the inconvenience arising from giving extended 

 ranges to species, upon the occurrence of stray and even doubtfully 

 recorded specimens, by ]3lacing an asterisk in the columns under 

 which a species is most at home. We have also endeavoured to 

 separate species of the Upper Bracklesham Beds from those of the 

 Lower ; and, though necessarily imperfect, this arrangement cannot 

 fail to be of value in showing the passage of the fauna in a truer 

 light than hitherto. 



A formidable obstacle was presented by the extensive synonymy 

 in use. Ko less than 42 species from Barton, out of 182 in the 

 catalogue of the museum at Jermyn Street, cannot be traced under 

 the same names in Edwards's list, whilst in the latest of the lists given 

 by Prestwich 65 additional names of Barton fossils occur which are 

 ignored by Edwards. Similarly we find 60 names in Morris's cata- 

 logue unrepresented, and 24 out of the 86 species recorded from 

 the Barton Beds of Alum Bay in the Survey Memoir on the Isle of 

 Wight of 1862. We have taken every precaution that no species 

 should be omitted, but have not thought it necessary to state our 

 reasons for changing or excluding names. Finally, we have not 

 given MS. names of Edwards in ecctenso, but have noted the number 



