x TEXT-BOOK OF ENTOMOLOGY 



PAGE 



b. Appendages of the head 57 



The antennae 57 



The mandibles .......... 59 



The first maxillse 62 



The second maxillae . . . . . . . . <!8 



The hypopharynx 70 



Does the hypopharynx represent a distinct segment ? .82 



THE THORAX AKD ITS APPENDAGES ........ 86 



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



The patagia .......... 89 



The tegulse 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 . . . . . .111 



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 



g. Mechanism of flight . . . . . . . . .148 



Theory of insect flight 150 



Grabers views as to the mechanism of the wings, flight, etc. . 153 



THE AHDOMEX AND ITS AFPKND.VI.KS ........ 162 



The median segment 163 



The cercopoda H',4 



The ovipositor and sting 167 



The styles and genital claspers (Rhabdopoda) . . . . 176 



Velum penis 181 



The suranal plate 181 



