VI PREFACE. 



repetition, a fault that I have found it equally difficult to 

 avoid in other parts of the book. 



Throughout the book generic names are printed in italics ; 

 and italics are used in the accounts of the type skeletons for 

 the names of membrane bones. Clarendon type is used to 

 emphasise certain words. In the classificatory table the 

 names of extinct genera only, are printed in italics. 



In a book in which an attempt is made to cover to some 

 extent such a vast field, it would be vain to hope to have 

 avoided many errors both of omission and commission, and 

 I owe it to the kindness of several friends that the errors are 

 not much more numerous. I cannot however too emphatically 

 say that for those which remain I alone am responsible. 

 Messrs C. W. Andrews, E. Fawcett, S. F. Harmer, J. Graham 

 Kerr, and B. Rogers have all been kind enough to help me 

 by reading proofs or manuscript, while the assistance that I 

 have received from Dr Gadow during the earlier stages and 

 from Prof. Lloyd Morgan and Mr Shipley throughout the 

 whole progress of the work has been very great. To all these 

 gentlemen my best thanks are tendered. 



All the figures except 1, 35, 55, and 84 were drawn by 

 Mr Edwin Wilson, to whose care and skill I am much in- 

 debted. The majority are from photographs taken by my 

 sister Miss K. M. Reynolds or by myself in the British 

 Museum and in the Cambridge University Museum of 

 Zoology, and I take this opportunity of thanking Sir W. H. 

 Flower and Mr S. F. Harmer for the facilities they have 

 afforded and for permission to figure many objects in the 

 museums respectively under their charge. I have also to 

 thank (1) Prof, von Zittel for permission to reproduce figs. 27, 

 41, 52, 69, 70, 80, 106 A, and 107 c; (2) Sir W. H. Flower 

 and Messrs A. and C. Black for figs. 1 and 84; (3) Prof. O. C. 



