viii PREFACE 



the Progressive Science Series, which is devoted to 

 the exposition of larger subjects than the present 

 appears at first sight to be. It has, however, been 

 my attempt in the present volume to endeavour to 

 illustrate by means of the group of whales a very 

 important biological generalisation, the intimate rela- 

 tion between structure and environment. No group 

 shows this to a more striking degree than that with 

 which I have occupied myself. 



The section on the Delphinidae will, I fear, be 

 found less interesting than those relating to other 

 subdivisions of the whale tribe. They are not, as 

 a rule, sufficiently well known to have accumulated 

 much anecdote ; and the structural differences present 

 nothing of importance save to the systematist. How- 

 ever, it is clearly necessary to include them, as 

 they form the bulk of the known Cetaceans. Their 

 synonymy, too, is perplexing and far from settled. 

 I have, as will be seen, followed True in the main, 

 adopting some subsequent alterations of his views. 

 As the present volume is not in any sense a catalogue 

 of whales, I have forborne from giving a synonymy 

 in the orthodox way ; but I have mentioned most 

 of the names which have been at one time or another 

 applied to dolphins. Those who desire to pursue 

 this portion of the subject further can refer to Mr. 

 True's account of the family Delphinidae, which is 

 frequently referred to in the text. 



I may remark, finally, that a large number of the 

 actual facts have been verified, and that here and 

 there some small details appear which have not been 

 hitherto recorded. 



