PREFACE 



principal object with which this volume has been written 

 is to present as full and complete an account of the Biology 

 of the Odonata as it is possible to offer in the present state of our 

 knowledge of these insects. Thus the book is written primarily 

 for biologists rather than systematists. More than ninety per 

 cent, of the papers so far published on the Odonata have been 

 chiefly systematic in their aim. ' The remainder are principally 

 morphological, and form a valuable though somewhat small 

 collection of facts on which a book of this kind must necessarily 

 be based. During the last three years, I have fortunately been 

 able to undertake a considerable amount of work on the internal 

 anatomy of the Order, thereby not only confirming many points 

 which were more or less in doubt, but also adding some new dis- 

 coveries, and here and there rectifying errors. Most of this work 

 has not yet been published, and will first see the light in the 

 condensed form in which it appears in the present volume. It 

 is hoped that the method of treatment followed in this book, 

 by which the morphological, phylogenetic and physiological 

 view-points have been correlated, in so far as our present know- 

 ledge allows, will enable students of the Odonata to take up 

 any line of research on this interesting Order with a full know- 

 ledge of what has already been achieved. To this end, the 

 Bibliography has been practically confined to those publications 

 bearing on the biological study of the Order. It would have 

 been impossible to include a complete list of the enormous number 



