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ON SOME REMARKABLE AUSTRALIAN 

 LIBELLULIFjE. 



By R. J. Tillyard, M.A., F.E.S. 



Part ii. Descriptions of new Species. 



(Plate xiv.) 



The numerous Libellulinai which are found in the tropical 

 regions of Queensland afford a most interesting study to the 

 naturalist. Many of them, of course, are forms found also in 

 New Guinea or in the other islands lying northwards from Aus- 

 tralia, but we also find some remarkable exceptions which are 

 distinct from the island forms, yet very closely allied to them. 

 One may safely say, however, that the time that has elapsed 

 since the tropical oceanic Libellulince invaded northern Australia 

 and settled there has scarcely yet been sufficient for the forma- 

 tion of many new species. Variation has taken place along 

 unexpected lines, and the result has been rather to upset some 

 of the current ideas of the true value of certain venational char- 

 acters to which European authors had given undoubted generic 

 value. The general tendency of the Libellulince of northern 

 Australia appears to be one of gradual simplification, which can 

 be noticed as taking place in the following ways : — 



1. Abolition of superfluous nervures, shown by change from a 

 once or twice-crossed triangle to a free triangle, or a reduction 

 in the number of rows of discoidal cells following the triangle. 

 Probably the same tendency operated in the formation of the 

 heteromorphic females of Neurothemis; and it is interesting to 

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