INSECTS. 



85 



which in this way obtain the requisite amount of 

 oxygen. The stigmata on one side of a caterpillar are 

 clearly shown in Fig. 60, and those of a hornet larva 

 in Fig. 61. 



Four classes belong to this sub-kingdom : Insecta 

 (Insects), Myriapoda (centipedes, etc.), Arachnoidea 

 (spiders, scorpions, etc.), Crustacea (crayfish, crabs, 

 lobsters, etc.). 



CLASS I. : INSECTA (INSECTS). 



Breathe by trachese (cp. p. 84). The segments 

 fuse into three body regions (Fig. 57). These are — 



Fig. 67.— a GrasBhopper, with the different regions of the body separated from 

 one another. A, head ; B, thorax : /., prothorax ; //., mesothorax ; III., meta- 

 tborax ; C, abdomen ; a, antcnnte ; 6, eyes ; c, d, e, legs ; /', g, wings; p, shank ; 

 q, foot. 



