Acknowledgments 



I should like to thank the many people who have helped either 

 directly or indirectly in the writing of this book. In particular, 

 I am indebted to the foundations laid by Professor Sir James 

 Gray, Dr H. W. Lissmann, and Dr S. Smith when teaching the 

 part of the course in Vertebrate Zoology which forms the basis 

 of several of the chapters. 



Three figures are taken directly from other publications and I 

 am grateful to the following authors and publishers for permit- 

 ting their use in this book: Professor G. E. H. Foxon and the 

 Cambridge University Press for figures 30 and 31 ; Drs Dawes, 

 Mott, Born, and Widdicombe, and the Long Island Biological 

 Association for figure 37. 



I also wish to thank the authors of publications from which 

 some of the other figures have been redrawn. When the refer- 

 ence is not given in the legend it will be found in the 'Further 

 Reading' section. 



For his guidance through the diverse problems that have 

 arisen during publication, it is a pleasure to thank Mr Hamish 

 MacGibbon of Heinemann Educational Books Ltd. 



I also wish to thank my wife for her help at all stages in the 

 preparation of this book. 



March 1963 G. M. H. 



In this reprint an index of animals has been added and a number of 

 alterations have been made to the text. For their advice on the amend- 

 ments I am most grateful to a number of friends and colleagues, 

 especially Dr G. S. Carter, Dr J. F. Mott and Dr J. A. Ramsay. 

 November 1964 G.M.H. 



