THE STUDY OF INSECT LIFE 23 



head, thorax, and abdomen ; the head provided 

 with mouth parts, eyes, and one pair of antennae; 

 the thorax with three pairs of legs; and the 

 abdomen, in all probability with caudal appen- 

 dages. If these views are correct, the genus 

 Campodea must be regarded as a form of 

 remarkable interest since it is the living repre- 

 sentative of a primeval type, from which not 

 only the Collembola and Thysanura, but the 

 other great Orders of insects have derived their 

 origin." 



While a certain amount of divergence of 

 opinion still exists concerning the still more 

 primitive group from which the Campodea type 

 was derived, the generally accepted opinion 

 held by most biologists is that these wingless 

 " Bristle-tails," which probably represent primi- 

 tive forms, may be traced back through some 

 of the less specialized Millipedes to the curious 

 caterpillar-like Peripatus, which in the details 

 of its anatomical structure unites the tracheae 

 of an insect and the nephridia or kidneys of 

 a worm. This Peripatus is a most interesting 

 and remarkable creature, belonging to a genus 

 which occupies a unique position between the 

 myriapods (Centipedes and Millipedes) and 

 insects on the one side, and the annelids or worms 

 on the other. The distribution, which is very 

 wide, the interesting structure, and the develop- 

 ment of Peripatus all suggest that it is the 

 survivor of an archaic type. It is a handsome 

 little creature, with a plump, round, unsegmented 

 body, about two inches in length ; numerous 

 two-clawed feet, and upon the head a pair of 



