642 ON SOME REMARKABLE AUSTRALIAN LIBELLULIN^, 



nervure, while in the Australian A. allogenes this triangle is 

 always free. This character actually demands either that a new 

 genus should be instituted for A. allogenes (the cross-nervule of the 

 forewing triangle being included in the original definition of the 

 genus A grionopter a) or else that the definition of the genus should be 

 extended to include A. allogenes. Dr. Kis' opinion is that in spite 

 of the remarkable difference in the triangles, the two forms must 

 be placed in the same genus, and are probably not even more 

 than subspecies or geographical races of one widely diffused and 

 variable species. In Agrionoptera, as in Nannodytliemis (which 

 1 have already dealt with in Part i. of this paper) lack of sufficient 

 material from many localities has caused the genus to be founded, 

 partly at least, on an important character which was accepted as 

 constant and of generic value, whereas the discovery of this new 

 Australian form, so closely allied to the type A. insignis Ramb., 

 shows us the necessity for revising our classification of the group 

 and eliminating from the generic definition a character which is 

 not shared in common by all its members. 



In the markings of thorax and abdomen, the four species A. 

 insignis Ramb., A. quatuornotata Br., A. similis Selys, and A. 

 allogenes are extremely similar, and the individual variation of 

 specimens is sufficient to prevent us from drawing a hard and 

 fast distinction between them; A. similis and A. allogenes, how- 

 ever, differ from A. insignis and A. quatuornotata by having only 

 one submedian cross-vein instead of tico. 



Note. — In the description of this species formerly made by me, 

 and referred to above, I compared this beautiful insect with the 

 larger Lathrecista festa, an insect of similar form and habits. At 

 that time I possessed only three immature examples of the latter 

 of an orange-brown colour; and this led me into the error of 

 saying that A. allogenes "is far more brilliantly coloured than L. 

 festa." On my recent visit to Cooktown, however, I took a fine 

 series of L. festa (£) and also some A. allogenes (£), both mature; 

 and I can now correct my statement, and say that of all the 

 brilliant red dragonflies I have seen in Australia, L. festa is 

 perhaps the most brilliant, outrivalling even such vivid insects 



