314 THE PANORPOID COMPLEX, i., 



evolved simply by loss of the archaic ju^al lobe, with correlated 

 reduction in size and strength of the hindwing, as it became 

 more and more dependent upon the fore in fliglit. 



The most ancient type of frenate coupling is that preserved 

 for us in the females of the whole series, where the bristles 

 remain short and unspecialised, and the retinaculum is formed 

 simply from the brush of stiff hairs or scales, that project for- 

 wards from the underside of the cubitus on the foi-ewing. 



In the males, there is a higher degree of specialisation, the 

 frenular bristles becoming fused together and greatly lengthened, 

 while a new and more effective retinaculum is developed from 

 the underside of the radius in the forewing, in the form of a 

 posteriorly projecting hasp or catch of chitin. 



(9) The amplexiform types amongst the Lepidoptera Hetero- 

 neura are to be regarded as a series of separate developments 

 (probably three in number) from originally frenate ancestral 

 forms. Of these, the most evident connection would appear to 

 be that uniting the frenate Ca^tiiiid(p, with their well developed 

 humeral lobe and clubbed antennae, with the very similar but 

 non-frenate IJpsiwriidfP. 



(10) The only portion of the original coupling-apparatus left 

 in the highly specialised Order Diptera is the jugal lobe, which 

 becomes enlarged to form the aJula. 



We may now exhibit, in the form of a short Table, the state 

 of the coupling-apparatus in the various existing groups, to which 

 we must add the Archetypes of the several Orders, as these 

 results will be required in the final discussion on the Phylogeny 

 of the Orders. (See pp. 3 16-3 17). 



