2 PREFACE. 



altered, and the known Eocene Mollusca intended to be comprised in his work have since 

 then been so largely augmented in number, as seriously to impede his progress, and 

 to compel him to change his original intention. The prospect once entertained by Mr. 

 Edwards of completing the whole of the Eocene Mollusca thus became so remote that 

 he proposed to me that, as my monograph on the Crag was finished, I should describe 

 the Bivalves of the older Tertiaries. 



From a knowledge of the amount of labour my friend has before him ere he 

 reaches the termination of the Univalves, which must occupy him for many years to 

 come, I was induced to consider whether any assistance that I could render in the 

 illustration of these fossils would not be of service to the science of Geology. I felt 

 at first especially reluctant to interfere in any way with a work that has been so 

 ably conducted, but the great desire expressed by Tertiary Geologists to possess an 

 illustration of the Mollusca of the Eocene period in this country still unfigured and 

 nndescribed was an inducement to make all other considerations subordinate to that 

 imperious want, and on that ground alone I have consented to attempt to supply 

 .such a desideratum. Mr. Edwards has in the most liberal manner promised to place 

 the whole of his Bivalves in my hands, as they may be wanted for examination. His 

 collection of these fossils is the most perfect I have seen, and as the work was intended 

 to be done by himself, the type specimens have and will be taken from his cabinet, except 

 where otherwise particularly expressed ; and the principal localities will be introduced on 

 his authority. Mr. Wetherell, Dr. Bowerbank, Mr. Prestwich, the Rev. Osmond Fisher, 

 and all my geological friends, have most kindly permitted me the use of any specimens 

 in their cabinets, and I have to return them my best thanks for their assistance, with- 

 out which my work would be very incomplete. Mr. Wetherell's collection is parti- 

 cularly rich in the fossils of the London Clay from the north side of London ; and Dr. 

 Bowerbank's more general collection possesses some choice and unique specimens. To 

 Mr. Prestwich I am further indebted for some of his typical specimens, and more 

 especially for his assistance in regard to localities. Neither must I omit to mention 

 that our national museums contain many specimens that have already been used 

 for the illustration of the Bivalves of these older Tertiaries, or which will materially 

 contribute to that object ; and I beg to express my obligations to the conservators of 

 these treasures, who have in the most handsome and friendly manner given me every 

 possible facility and assistance in the promotion of my undertaking. The utmost desire 

 of every one connected with Palaeontology appears to have been shown to assist in 

 forwarding the good work undertaken by the Palaaontographical Society. 



S. V. WOOD 



March, 1861 



