258 AUSTRALIAN PSYLLlDuE, 



All the species that I have examined appear to fall very 

 naturally into the subfamilies defined chiefly upon the structure 

 of the wings by F. Low. Those forming lerp-scales or hiding 

 under bark are referable either to the Liviince or Aphalarince; 

 most of those living among flocculent matter upon foliage or 

 forming rudimentary lerps to the Psyllium; and all the true gall- 

 producing species (with a few exceptions) to the Triozince. 



I have not proposed new genera for any species that I could 

 at all reasonably refer to genera already well-defined ; and if I 

 have erred on the side of ca.ution, specialists will be able to rectify 

 this defect. This course appears to be preferable to forming new 

 genera on such scanty material, as has been done in the past: one 

 of AValker's genera, for instance, being based on the examination 

 of a single specimen minus the head. 



In a large series of specimens one frequently meets with 

 examples possessed of an extra cell or cross nervure in the wings; 

 such, if examined alone, would certainly not fit the genus to 

 which the species belongs. It also appears to me that some of 

 the latest genera established by Riley and others are so minutely 

 defined that they can only take in the single species upon which 

 they are founded, whereas if they had received more general 

 treatment they might have included all allied forms. 



In Schwarz's paper (10) he discusses the position of the genus 

 Spondyliaspis, to which he refers the typical lerp-producing species, 

 Psylla eucalypti, Dobson; and he comes to the conclusion that "the 

 peculiar structure of the hind tibice and tarsi possesses more than 

 a generic value"; and he according^ proposes a new subfamily, 

 Sp>ondyliaspiiue. But as all the subfamilies previously established 

 have been defined almost entirely upon the structure of the fore- 

 wings, I should prefer to see it remain in the Aphalariiue. 



The following comprises a list of the genera placed in the first 

 two subfamilies. 



Family PSYLLID^E, Latr. 

 i. Subfamily LIVIIN^, F. Loew. 



Front of head not produced into conical processes; eyes not 

 prominent. Stalk of cubitus shorter, as long as, or longer than 



