ODONATA. 75 



without loosening its connection or the connection of 

 the neck with the prothorax. 



The prothorax (PI. III., Figs. 32,35, ^') is very small, 

 and is not carried backward like that of the locust, but 

 extends like a narrow, chitinous collar around the neck. 

 On the dorsal side it is distinctly marked off into three 

 transverse portions, and the middle one is again divided 

 by a longitudinal suture. It is freely movable, and 

 by being so gives greater range of motion to the head. 

 If, now, the upper posterior margin of the head is 

 examined, it is seen to curve forward, so that the head 

 can be thrown back over the neck and prothorax, 

 meeting no considerable resistance till it is applied to 

 the convex surface of the mesothorax. When we con- 

 sider that the dragon-fly catches its food " on the 

 wing," a habit which will be referred to again when 

 describing the mouth parts and legs, the necessity for 

 this free motion of the head is at once recognized.^ 



The mesothorax (PL III., Figs. 32, 35, ^") and meta- 

 thorax (Figs. 32, 35, //") are greatly developed, and 

 contain the powerful muscles which govern the actions 

 of the wings ; they are also firmly consolidated, the 

 suture showing in Fig. 35, sut. The dorsal and ventral 

 portions are narrow, but the lateral parts rise like high 

 walls on either side (see Fig. 35). The mesothorax 

 extends above the head in front, and the abdomen 

 behind, giving a hunch-backed appearance to the 

 insect. Both rings incline downward and forward, 

 and the legs are attached to the extreme anterior por- 

 tion of each ring, in obedience to the law of habit, as 



1 See also p. 78. 



