94 



ANIMAL BIOLOGY 



L THYSANURA 



VII. EPHEMEROPTERA 



ANNELID-LIKE ANCESTOR 



Fig. 54B. — General relationships of the chief orders of the class Insecta. 

 I, Silver-fish; II, Springtail; III, Praying mantis; IV, Earwig; V, Termite; VI, 

 Stonefly; VII, Mayfly; VIII, Dragonfly; IX, Lacewing fly; X, Scorpion fly; 

 XI, Caddice-fly; XII, Stable fly; XIII, Flea; XIV, Butterfly; XV, Bird louse; 

 XVI, Cootie; XVII, Book louse; XVIII, Thrips; XIX, Cicada; XX, Triatoma 

 Idssing bug; XXI, Potato beetle: XXII, Bumble bee. In general, the classi- 

 fication is based on the presence or absence of wings, the structure of the mouth 

 parts, and the character of the life history. See page 478. (From Hegner.) 



