BY R. J. TILLYARD. 295 



These developments must be regarded as isolated specialisations, 

 which must be expected to occur throughout an Order in which 

 all parts of the wing remain so well provided with hairs as in 

 the Trichoptera. 



From the above evidence, we must conclude that the Arche- 

 type of the Trichoptera already possessed a highly reduced 

 coupling-apparatus, in which only one of the four original paits 

 w as represented, viz., the jnyal lob'-. This type may be designated 

 as the archaic jnyati' type of wing-coupling. 



Order DIPTERA. 



In this Order, owing to the loss of the hind wings, there is no 

 longer any need for a coupling-apparatus. But we can recognise 

 the jugal lobe of the forewing, in the form of the basal lobe 

 known as the aJala in this Order. 



It is clear, therefore, that the Archetype of the Diptera re- 

 sembled that of the Trichoptera in possessing the archaic jugate 

 tijpe of wing-coupling, in which only the jugal lobe is present. 



AVe might note here, parenthetically, that, in the other Holo- 

 metabolous Order (the Coleoptera), in which flight is carried on 

 by only one pair of wings, there may still be found evidences of 

 the original presence of a jugal lobe; e.g., in certain Hydro- 

 philidfP, where this lobe is quite large and conspicuous, though 

 it does not seem to perform any definite function. 



Order LEPIDOPTERA. 



(Text-figs. 10-16, and Plates xxix.-xxx., figs. 18). 



We have kept this Order to the last, because, within it, there 

 are developed the most surprising and interesting of all the 

 specialisations arising from the old type of basal coupling-appa- 

 ratus, which we have already studied in the other Orders of the 

 Complex. 



It has been frequently stated that certain families of INIoths, 

 viz., the JJicropterygidce {sena. /at., including the Eriocraniidcp) 

 and the HepiaUdcH, are distinguished from all other Lepidoptera 

 by the nature of their wing-coupling apparatus. To these, Mey- 

 rick(9) has lately added a third family, the Frutotheoridce, which 



