XV] ZOO-GEOGRAPHICAL DISTRIBUTION 293 



Uropetala, Austropetalia and Synlestes, which are included in the 

 section on Palaeogenic Fauna, for the reasons there stated, we 

 note the occurrence of the following groups : (i) two very archaic 

 genera of Gomphini, (ii) a very rich Aeschnine fauna belonging 

 to the Brachytronini, and paralleling the development of Aeschna 

 in the Northern Hemisphere, (iii) the very interesting and graceful 

 tribe Syntkemini, (iv) six genera of Idocorduliini, (v) three genera 

 of Tetrathemini, (vi) a special development of numerous small 

 bronze and blue Lestinae (Austrolestes), bionomically parallel with 

 Agrion and Enallagma of the Northern Hemisphere, (vii) a fairly 

 rich fauna of Megapodagrioninae and Protoneurinae, (viii) six 

 peculiar genera of Agrioninae. 



The immense development of Corduliinae, totalling 16 genera 

 and 52 species, is probably the most striking feature of the 

 Australian fauna. Besides the archaic forms already mentioned, 

 we must also notice the extraordinarily specialized Cordulephya, 

 the mysterious Pentathemis, and a fairly strong development 

 of Eucorduliini, paralleling that of the Northern Hemisphere. 

 The species of the latter have been referred to Somatochlora, 

 Procordulia and Hemicordulia. Of these the last genus is the most 

 specialized, and resembles Anax in the adoption of a rounded 

 hind-w T ing in the male, and also in the startling success of its new 

 career, since it has already overrun the Oriental region and 

 Madagascar. 



Besides the very archaic groups which form the basis of the 

 fauna, there are a number of isolated side-branches, all highly 

 specialized, which seem to have found their way into the region 

 long ago, and followed their own lines of development. Of these 

 we may mention Austrothemis (paralleling Leucorrhinia of the 

 Northern Hemisphere), Diphlebia (the most Agrionid-like of all 

 Calopterygidae), the wonderful little Hemiphlebia, and the exces- 

 sively reduced Australian Protoneurinae. These last probably 

 represent the most highly asthenogenetic Dragonflies yet evolved. 

 The very remarkable genus Lestoidea (fig. 154) combines an 

 essentially Protoneurine venation and facies with certain Mega 1 - 

 podagrionine characters. 



In the Papuan province the most striking facts are the rich 

 developments of the Gynacantha-Series and of the Libellulinae, 



