198 



The Orders of Insects 



state. The prothorax and metathorax are small, the 

 mesothorax large. There are ten evident abdominal 

 segments, the hindmost with a pair of very long, 

 jointed cercopods, and often with a similar median 

 appendage also. The legs are slender, the front 

 pair being the longest. The forewings are much 

 larger than the hindwings, which in'some forms (e.g. — 

 Cloeon) are quite absent ; a large number of cross 



Fig. III. — yiay^y (E/>ken!era vulgaia, Linn.) Europe, natural size, 

 and larva, magnified. 



nervules between the longitudinal nervures causes a 

 complex network on the wing surfaces (125). In one 

 character of internal structure the Mayflies are the 

 most primitive of all winged insects ; the genital 

 ducts are not only destitute of chitinous lining, as 

 in Earwigs, but remain paired throughout life (49). 

 Development. — The eggs are dropped into water 



