x TEXT-BOOK OF ENTOMOLOGY 



PAGE 



b. Appendages of the head .... .57 

 The antennae .......... 57 



The mandibles .59 



The first maxillaj .62 



The second maxillae ...... .68 



The hypopharynx .... 70 



Does the hypopharynx represent a distinct segment ? . . 82 



THE THORAX AND ITS APPENDAGES ...... .86 



a. The thorax : its external anatomy ... .86 



The patagia .89 



The tegulae .89 



The apodemes .92 



The acetabula .... .94 



b. The legs : their structure and functions ... .95 



Tenent hairs .99 



Why do insects have but six legs ? . . . . . 100 



Loss of limbs by disuse ........ 101 



c. Locomotion (walking, climbing, and swimming) .... 103 



Mechanics of walking . 103 



Locomotion on smooth surfaces ...... Ill 



Climbing .116 



The mode of swimming of insects 116 



d. The wings and their structure 120 



The veins .121 



The squamae ........ . 123 



The halteres .124 



The thyridium .124 



The tegmina and hemelytra .... . 124 



The elytra .124 



e. Development and mode of origin of the wings . . 126 



Embryonic development of the wings ... .126 



Evagination of the wing outside of the body . .132 



Extension of the wing ; drawing out of the tracheoles . . 133 



/. The primitive origin of the wings .... . 137 

 The development and structure of the tracheae and veins of 



the wing .... .144 



y. Mechanism of flight 148 



Theory of insect flight .... 150 

 Graber's views as to the mechanism of the wings, flight, etc. . 153 



THE AllDOMEN AND ITS APPENDAGES . 162 



The median segment 163 



The cercopoda . . 164 



The ovipositor and sting . 1 (>| 7 



The styles and genital claspers (Rhabdopoda) . . 176 



Velum penis . . .181 



The suranal plate 181 



