THE WINGS. 



615 



elytra. In them the chitinous cuticle is much thickened and 

 the upper and lower surfaces are clamped together by minute 

 chitinous pillars. Between these layers, fat-bodies and cells 

 containing uric-acid concretions, as well as nerves, tracheae and 

 blood are found. 



The fore- wings of the Strepsiptera are replaced by small 



FIG. 338. A, right half of thorax of Anopheles maculipennis with base of right wing and 

 right halter. Magnified 40 times. B, the same magnified about 7 to show the 

 area which bears the stridulator. This is shaded. R toothed bar ; A* the teeth which 

 rasp on the ridges borne by B ; B blade bearing the ridges R ; C trough which limits the 

 movements of B ; D distal chitinous sclerite bearing a claw which works in .D 1 the hollow 

 at the base of B ; D 2 joint betwesn D and E ; E intermediate sclerite between D and F ; 

 E^ hinge between E and F ; F proximal sclerite which is inserted into the thorax beneath 

 the scutellum ; Ft- process on F ; G thickened edge of squama ; G 1 fold of squama over- 

 hanging E and D ; H process of chitin which overhangs the base of the blade ; K distal 

 end of halter ; L concave area covered with papillae ; M knob ; MI hinge ; N papillae 

 on knob (from Shipley and Wilson). 



membranous appendages. In the Diptera the hind-wings 

 are replaced by the above mentioned halteres, which are 

 usually clubbed and well provided with sense-organs. In 

 most of the more primitive orders the fore- and hind-wings 

 are quite unconnected and move independently, but in many 



