66 ELEMENTARY LESSONS ON INSECTS 



5. Chase a flat nymph about the surface of a stone and 

 see how it runs sidewise, with legs extended and claws 

 gripping the surface. 



B. Study of Preserved Materials 

 a. Adult 



With specimens outspread for examination first observe 

 whether both imagos and subimagos are present (the latter 

 dull-surfaced, as stated on p. 64, and sometimes more deeply 

 colored). Then, with either, note the following peculiarities 

 of the order: 

 The softness of the body and the slenderness of its 

 fragile appendages. The long front legs extended for- 

 ward, balancing the long tails extended backward. 

 Both serve as "outriggers" in flight. The mayfly does 

 not walk. It stands on middle and hind legs, holding 

 the front ones extended forward. Then note further: 



I. In the head. 



1 . The absence of mouth parts, except for mere f unctionless 

 rudiments of jaws. 



2. The minute bristle-like antennae. 



3. The huge compound eyes, larger in the male, each more 

 or less separated into two divisions, upper and lower, 

 having facets of different size. 



4. The nose-like ridge on the face and the three ocelli 

 above it. 



