95 



Genekal Remarks on the Genera of the CiCADiE 



ALREADY DESCRIBED. 



At the close of this description of the Deltocephahclas, 

 a review of certain facts brought to notice in the pages 

 of the previous, and in those of the present, volume, 

 may here be conveniently discussed. Materials for a 

 study of the foregoing genera, and the numerous 

 species of the tribe of insects for which I have 

 suggested the title Tettigidae, seem here to offer them- 

 selves, and they may perhaps decide how far I have 

 been justified in placing these non-stridulating insects 

 amongst the true Cicadae. 



It may here be urged that the presence or absence of 

 stridulating organs is not sufficient of itself to separate 

 species which in other respects very generally agree. 

 Even the consideration of wing-neuration, at one time 

 so strongly advocated, cannot alone decide this question. 



Differences between the extreme examples furnished 

 by the Centrotidse and the Deltocephalidae, to say 

 nothing of the lower forms of the Typhlocybidse, 

 shortly to be described, seem to be greater than 

 between the stridulating genus Cicadetta and examples 

 furnished by Macropsis, Cixius, Tediopsis, Thamnotettix, 

 &c. Apart from the marked differences in size, one can 

 hardly doubt, from their general aspect, that these 

 insects have close relations to known families. 



If Cixius and Macropsis are not admissible amongst 

 Cicadinae, there seems to be no alternative to placing 

 them in a separate group, which nevertheless appears 

 to be quite unnecessary. 



Morphologically I cannot separate these genera with 

 any sharpness; and therefore I assign to the Tettigidse 

 an equal tribal position amongst Trimerous Homoptera 

 to that taken by the Psylhdae and Aphidae amongst 

 Dimerous Homoptera. 



In all the genera, indeed, of this family of insects, 

 certain organs seem formed on similar types. The 



