BY R. J. TILLYARD. 



189 



considerable reduction during its migration eastwards. Tt may, 

 in fact, be considered as very probably a specialised offshoot from 

 the Oriental genus Burmagomphns^ and its arrival in Australia 

 is almost certainly much more recent than that of Ausfrofjomjyhus, 

 s.str. As for the latter, its origin seems lost in the mists of 

 antiquity, since no other Goniphiiice are, so far, known in whicli 

 the larval rectal gills have not developed papilla'. Both genera 

 must hav^e entered Australia from the North-West by way of 

 Timor, since no Gomphiruc occur in the Papuan subregion. 



Needham's supposition, that Aj may possibly be aborted in 

 the Gomphinff, seems to me to be unlikely. For, in the more 

 primitive forms, it is just this particular branch of A which 

 shows the greatest development. It seems rather that we have 

 to do with forms in which Ao is very poorly developed, this being 

 due to the fact that the failure of A^ to reach Cii., left only a 

 very small area between A3 and Aj, for Ag to supply. 



Having now followed the development of the anal trachea in 

 both fore and hind wings through all its phylogeiietic stages, we 

 may conclude this section by giving a table of the principal 

 differences between the Comstock-Needham notation and the new 

 notation here adopted : — 



Main longitudinal veins at base 

 of wing : — 



First 



Second 



Third 



Fourth 



Fifth 



First eubito-anal cross-vein ^ 

 ( = Anal-crossing) j 



Anal loop of uEschnince : — 



Basal side 



Distal side 



Italian loop of Liheilulidcp : — 



Basal side 



Midrib 



Distal side 



Sole of foot 



Corns tock-Need ham 

 Notation. 



C 

 Sc 



R + M 

 Cu 

 A 



(>nq{Kis) 



A„ 



a; 



AjiRis) 

 A„(Ri8) 

 A[(Ris) 

 9 



New Notation. 



C 



Sc 

 R + M 



Cu + A 

 A' 



Ac 



A, 

 Ai 



A, 



Cusp! 



Cu, 



CUi!,, 



Note on the so-called ^^ First Postcubital ." — In Plate xi., fig. 3, 

 I have shown the tracheation of the hind^ving of the nymph of 



16 



