4i6 



NEUROPTERA 



CHAP. 



verify tEis by actual observation, as the act of capture and trans- 

 fer is so very brief and is performed in the midst of a rapid 

 dash of flight, but it seems more probable that the prey is first 

 struck by the legs than that the mouth is the primary instrument 

 of capture. The excessive mobility of the head permits the victim 

 to be instantly secured by the mouth, and the captured fly is 

 turned about by this and the front pair of legs, and is nipped 

 rapidly so that the wings and drier parts fall off; the more 

 juicy parts of the prey are speedily squeezed into a little ball, 

 which is then swallowed, or perhaps we should rather say that 

 the mouth closes on it, and submits it to further pressure for the 



extraction of the juices. We 

 have already noted that many of 

 these large and active dragon- 

 flies, particularly in the Libellu- 

 linae and Aeschninae, have their 

 eyes distinctly divided into two 

 ^'^ parts, the facets in the lower 

 part of the eye being different 

 from those of the upper part. 

 Exner considers ^ that the upper 

 division is for the perception of 

 movement, the lower for the 

 perception of the form of rest- 

 ing objects. Plateau thinks^ 

 that the dragon -flies perceive 



only movement, not form. 

 Fig. 263. Inner view of a portion of mi i j- j , r n- i i. 



the left side of body of Libdhda de- ^^e Splendid acts of flight 



2)ressa, showing a part of the mechanism of the Anisopterid Odoiiata are 

 of flight, viz. some of the chitinous t i i i -i i p 



ridges at base of the upper wing, and accomplished by the aid ot a 

 some of the insertions of the tendons complex aiTancreilient of chitin- 

 of muscles. A, line of section through . 



base of upper wing, the wing being O^S pieceS at the baseS ot the 

 supi^osed to be directed backwards; C, lino's fFig". 263) 111 Ilisects 

 upper portion of mechanism of the _ & V 8* -^ ^ / 

 lower wing ; b, lever extending between witll Considerable pOWers of 



[A'ir:rLer,:ltd:) ' "^ '" " ^^8^* ^^'^ ^in^ wi.>gs are usually 



subordinate in functional im- 

 portance to the anterior, to which they are attached by a series 

 of hooks, or some other simple mechanism, on the wings. 



^ Physiol, facett. Aug. 1891, p. 115. 

 2 Bull. Ac. Belgique (3), xvi. 1888, No. 11, p. 31. 



