PREFACE TO THE SECOND EDITION 



rilHE favourable reception accorded to the first edition of this 

 book encourages the hope that, in its present form, it will 

 meet with similar success. The whole of the first section has 

 been rewritten. It has been enlarged so much that its publication 

 as a separate volume seems advantageous. More than eighty 

 illustrations have been added. The old illustrations have been 

 furnished with reference lettering in an uniform style, and many 

 of them have been re-drawn. This part of the work has been 

 carried out largely by Mr Parker, formerly assistant to the late 

 Mr Edwin Wilson, who also prepared several of the drawings. 

 The patience and care of both these artists demand mention here. 

 To the authorities and staff of the University Press I am 

 indebted for advice, and to Mr J. Whittingdale of Downing 

 College I owe the preparation of the General Index and the list 

 of illustrations. 



For photographs and for permission to copy or use cliches, 

 I wish to thank more especially the following persons and 

 institutions : 



Dr Gregory (of the American Museum of Natural History), 

 Professor Elliot Smith, Dr Charles Hose, Dr Brown, Dr Chalmers 

 Mitchell, Professors Sherrington, Griinbaum, Schlaginhaufen, 

 Schwalbe, Retzius, and Osborn ; the Publishing Committees 

 of the Royal Society and of the Royal Society of Medicine 



