viii INTRODUCTION. 



There are, in the Hunterian Collection of the Royal College of Surgeons, a considerable 

 number of fossil Crustacea from the London Clay, belonging to the following species : 

 Xanthopsia Leachii, X. bispinosa (?), Xanthilites Bowerbankii, Goniochele angulata, 

 Dromilites Lamarckii, Thenops Sci/llariformis, Hoploparia Gammaroides, H. Bettii, 

 Archaocarabus Bowerbankii. These are all from Sheppey, and constitute part of a 

 collection of fossils formed principally by Hunter himself, and now in the course of 

 arrangement in the museum under the care of Professor Morris. It is very interesting to 

 find that, amongst the immense riches belonging to the recent creation, collected by our 

 greatest comparative anatomist and physiologist, there are so many examples of the 

 " organic remains of a former world," most of which have since been, as it were, re- 

 discovered and described, without the least suspicion that even these ancient beings had 

 not escaped the grasp of that universal mind. 



To those gentlemen who have with the most unrestricted liberality and kindness placed 

 their treasures at my service, and especially to Mr. Bowerbank and Mr. Wetherell, whose 

 unrivalled collections have formed the basis of this work, my thanks are cordially rendered. 

 To Professor Sedgwick and Mr. Barrett, of Cambridge, to Mr. Woodward, of the British 

 Museum, to Professor Morris, to Mr. Prestwich, and other friends, I am also greatly indebted; 

 and the imperfections of this monograph can urge no claim to indulgence from the want of 

 the kindest sympathy and assistance from those who had the opportunity of rendering it. 



