163 



ON SOME PROBLEMS CONCERNING THE DEVELOP- 

 MENT OF THE WING-VENATION OF ODONATA. 



By R. J. TiLLYARD, M.A., F.E.S., Science Research Scholar 

 IN THE University of Sydney. 



(Plates xi.-xiii., and twenty text-figures.) 



Introduction. 



During the course of some researches into the tracheal system 

 of Odonate larvse, I had occasion to examine a very large number 

 of these interesting creatures. Thus a beautiful series of develop- 

 ing nymphal wings was presented to me, which it was impossible 

 to ignore or to cast away unexamined. Hence it was tliat I 

 determined to photograph the wings of each species, as oppor- 

 tunity offered, and to use them with a view to famiharising 

 myself with the problems and theories set forth by Needham in 

 his now famous paper.* 



It soon became evident that there were certain portions of the 

 question in hand that needed special attention, while new aspects 

 of the problem presented themselves to my mind and demanded 

 investigation. It seemed to me that the whole problem of the 

 development of the unique venation of the Odonate wing might 

 conveniently be divided into two parts, viz.: — 



i. 'J'he study of the tracheae of the developing wing, and their 

 relationships to the imaginal wing-veins. 



ii. The study of the source of the oxygen-supply of the wing- 

 tracheae. 



* Needham, J. G., "A genealogic study of Dragonfly Wiug-Veuation," 

 Proc. U. S. Nat. Mus., xxvi., pp. 703-764, 1903. 



