TABLE OF CONTENTS. 



Introduction .... 

 Review of previous literature on the group 



PAGE 



1 

 3 



CHAPTER I. 



On the classification of the Collembola and Thysanura 



31 



CHAPTER II. 



On the importance of the Collembola and Thysanura in rela- 

 tion to the evolution of the Insecta 

 Relation of the larva to the imago 

 Developmental and adaptive changes 

 The genns Campodea 

 Different classes of larvae 

 Importance of the mouth- parts 

 Possibility of changes in the mouth-parts 

 Nature and origin of the wings 



40 

 42 

 44 

 45 

 47 

 48 

 51 

 53 



CHAPTER III. 



Collembola — general description 



The head 



The thorax and the abdomen 



Specific differences 



Habits 



Internal anatomy . 



Embryology 



Nervous and muscular systems 



55 

 56 

 67 

 71 



72 

 73 

 84 

 89 



