314 MONOGRAPH OF THE GENUS SYNTHEMIS, 



detailed description," that even those who have no special know- 

 ledge of Australian Odonata will be able to use the plates with 

 advantage. 



Owing to the rarity of specimens of the genus, no detailed 

 study of it has been possible to entomologists outside Australia. 

 Doubtless many new species still lie hidden in out-of-the-way 

 parts of the continent. However, during five yeax's' collecting in 

 various localities, I have gathered together a great number of 

 specimens — every one of which has been carefull}?^ examined for 

 variation — and have studied their habits in the field. Further, 

 I have been fortunate enough, after long and careful search, to 

 discover, and identify by breeding, the larvae of no less than five 

 species, the only ones obtainable within a hundred miles of 

 Sydney. The life-histories of these I have worked out fairly 

 completely. 



Those who have studied the peculiar venational characters of 

 the wing of Synthemis claim, with justice, that it is the most 

 archaic form of Cordidine wing still extant (with the possible 

 exception of the "quadrilateral" genus Gordulephya). I hope to 

 shew in the present paper that the morphology of the larva 

 strongly supports this view. The peculiar character of the Aus- 

 tralian fauna is evident in every group, and evidence of it is by 

 no means absent in the Odonata. Such archaic and isolated 

 forms as Synthemis, Petahira, Telephlehia, and Fhyllopetalia are 

 of the greatest scientific interest. The study of their life- 

 histories especially should throw a great deal of light on the 

 present-day affinities of the larger and more dominant groups, 

 and enable us to trace the synthetic evolution of existing types. 

 The peculiar characters of the larvae of Synthemis, to be described 

 in this paper, are of especial interest, and throw new light on the 

 relationships of Gord^diince to other subfamilies. 



The objects of this paper are two. Firstly, to discuss the 

 morphological and ph3'siological characters of the group with a 

 view to a satisfactory scheme of subdivision for the genus, 

 and the placing of it in its correct position in the subfamily. 

 Secondly, to give a detailed descriptive account of the separate 



