290 THE PANORPOID COMPLEX, i., 



formed by fusion of an original set of jugal bristles, as seen in 

 Chorista. A frenulum is also present, but reduced in size. 



In all other representatives of this Order, the jugal bristles 

 appear to be either absent or very weakly formed; and the whule 

 coupling-apparatus shows a 

 gradual reduction from dis- 

 use, probably owing to a pro- 

 gressive weakening in the hi 

 tlight of these somewhat lazy 

 insects. Text-tig. 3. * 



The culmination of this tendency is to be seen in the highly 

 specialised HUfaridce,, in which fore- and hind wings have again 

 il ^-ii-^i.*;-^^ returned to complete independence in 

 "^"■''^'^^^^' llight, the wings becoming greatly nar- 

 rowed and elongated, with petiolation 

 '^ of their bases. The coupling-apparatus 

 D •■' ^^V/^ is here only represented by a vestige of 



the humeral lobe, from which projects a 



W^ sinule frenular bristle, which ci-osses a 



^S,..,^^ similar bristle developed from the ex- 



Text-tif'.4.t treme base of the forewing (Text-fig. 4). 



Reviewing the above evidence, it is clear that the Archetype 

 of the Order Mecoptera must have had the complete archaic 

 coupling apparatus fully developed, very much as it still exists 

 in the ancient Choriatidm to-day. 



Order PLANIPENNIA. (Text-fig.5). 

 In this Order, the coupling-apparatus is again best developed 

 in the more archaic families, notably in the Ilpvierubiicke (Text- 

 fif.5). Jugal bristles are absent; but the frenulum is repre- 

 sented either by one or two strong bristles {Jr). These bristles 



* Wing-coupling apparatus in Merope tuber Newm,, viewed from above, 

 showing the large, black tubercle at l^ase of forewing: /;/, humeral lobe; 

 ( X 40). 



t Reduced wing-coupling apparatus in HarpobiUacus tWyardi E.-F : 

 }), bristle developed from extreme base of forewing; other lettering as in 

 Text-fig. l;(x 40). 



