286 



THE PANORPOID COMPLEX. 

 Part i. — The Wing-coupling Apparatus, with special 



REFERENCE TO THE LePIDOPTERA. 



By R. J. TiLLYARD, M.A., D.Sc, F.L.S., F.E.S., Linnkan 

 Macleay Fellow of the Society in Zoology. 



(Plates xxix.-xxx., and sixteen Text-figures.) 



There can be little doubt that, in the original Pterygote 

 Insects, fore- and hindwings were independent in tlight, and the 

 muscles controlling them were innervated from two separate 

 sources, viz., the ganglia of the meso- and metathorax respect- 

 ively. Coincidence of action or beat, then, between fore- and 

 hindwings, without which flight would scarcely have become 

 possible, must have been maintained through coordination of the 

 two sets of nervous impulses sent out from these two ganglia. 



Now, in those Orders in w^hich the wings were more or less 

 hairy, the development of a fringe round the border of the wing 

 would undoubtedly increase the sense of touch in these organs; 

 since the macrotrichia, or larger seta? of the wing, are of the 

 type known as seufiilhe, and were evidently developed at first as 

 tactile organs. Hence it came about that, in the course of evo- 

 lution, a further coordination was able to be established between 

 the posterior portion of the base of the forewing and the anterior 

 portion of the base of the hind."**" Such coordination did not, at 

 first, take the form of a definite linking-up of the two wings, but 



* It should be borne in mind that the structures here to be discussed 

 were originally present on both wings; e.(j., frenular bristles occur at base 

 of foreirinys of certain Mecoptera, as well as of hindwings; and a jugal 

 lobe is pi^esent at bases of hofh wings in certain Trichoptera and in Micro- 

 pterj/yldfc. But it is onlj' on the posterior border of the forewing and the 

 anterior border of the hind that thej^ can come into contact, and so develop 

 into a coupling-apparatus. 



