﻿PREFACE. 



When I agreed to assist my deceased friend F. E. Edwards in the task of describing 

 the British Eocene Mollusca by taking the Bivalve portion, it was on the understanding 

 that the specimens in his collection (which embraced with few exceptions all the species 

 known from this Formation) should be placed in my hands, to be retained by me so 

 long as they might be required for examination and description, so that I might have 

 them constantly under my own eye for study and for comparison with the figures of the 

 French Eocene species and other published figures accessible to me. The failure of Mr. 

 Edwards's health put an end to the further prosecution of his portion of the work, viz. 

 the Cephalopoda and Gasteropoda, but I was enabled, by the means I have mentioned, to 

 issue another instalment of the Bivalvia in the volume of the Palaeontographical Society for 

 1870. Since then the collection has passed into the British Museum, and by this the 

 desideratum which I considered indispensable for the performance of my part of the 

 work became unattainable. I therefore gave up the idea of further prosecuting the 

 description of the British Eocene Bivalvia ; but finding that I had in my own cabinet 

 several species of Eocene Fluviatile Shells which had not been described, and being 

 kindly assisted by Messrs. C. J. Meyer, Caleb Evans, and the Messrs. Bott, with 

 the loan of specimens from their cabinets, I essayed to complete so much of the 

 work as would comprise the Fluviatile species of the Bivalvia, and with that 

 object the accompanying two plates were engraved. Domestic trouble obliged me, 

 however, to postpone even this part of the work, and I now find that, owing to my 

 advanced age and to the infirmity under which I labour, I am incapable of leaving home 

 and spending the time necessary for the thorough study of the species in the British 

 Museum which is essential to their satisfactory description. I have therefore, with much 

 regret, given up the idea of further describing the British Eocene Bivalve Mollusca, 

 and leave its completion to younger and abler hands, confining myself to a description 

 of the few species which have been thus engraved, and trusting that, under the circum- 



