BV R. J. TILLYARD. 291 



project from the apex of a very strongly developed humeral lobe 

 (h/). During Hight, this latter lobe, together with its frenulum, 

 passes under the jugal lobe of the forewing, which is hollowed 

 out beneath for its reception. 



The same type of coupling-apparatus is to be found in all the 

 other families, but it is generally much 

 reduced in size, and does not appear to be 

 functional. The tendency in the evolution 

 of this Order has been to combine a pro- 

 gressive narrowing of the wings with a 

 gradual return to complete independence 

 of fore- and hindwing in flight. In the 

 highest families, Mynnelaonfidce and Asca- Text-fig.o." 



laphid(f., the bases of the wings become shortly petiolate, and the 

 original coupling-apparatus can only be made out as an extremely 

 reduced renniant at the very bases of the wings. 



For this Order, then, we must assume an Archetype in which 

 the archaic coupling-apparatus was complete in all except one 

 particular, viz., that the jugal bristles were absent. 



Order MEGALOPTERA. (Text-figs. 6-7). 



Throughout this Order, the hairy vestiture of the wings, both 

 macro- and microtrichia, has been very much reduced. The most 

 archaic type of coupling-apparatus known to me within the Order 

 is to be found in a genus not yet described, but allied both to 

 the Corydalidce and the Sialidcn. This possesses both jugal and 

 humeral lobes, of small size, the latter with a few small hairs, 

 the remnants of the frenulum. In Sialis, the two lobes are 

 present, but apparently hairless. 



In the Corydalidce (Text-fig. 6), as exemplified by Archicha all- 

 odes, the only genus that I have been able to study, the humeral 

 lobe is much reduced, but the jugal lobe becomes a definite 

 angular projection (,y7) which presses down upon the costa of the 

 hindwing. Further, the forewing overlaps the hind for a con- 



* Wing-coupling apparatus in Drepanacra humilis McL., viewed from 

 beneath; ( x 24:). Lettering as in Text-fig. 1. 



