DELPHACID^. 27 



As the larger number of species live and feed on the 

 grasses and sedges which grow in swamps, and as 

 such broad flats are peculiarly open to rough winds, 

 we may suppose that insects having large wings, 

 unaccompanied by strong muscles capable of vibrating 

 the same, would often meet the accidents of draggling 

 their wings in the pools, or getting themselves drowned 

 outright. Thus, both males and females of such genera 

 as Liburnia and Stiroma might be beneficially affected 

 by a curtailment of these flying organs. Again, the 

 occasional appearance of the Macropterous forms of 

 both sexes would ensure the spread of the species over 

 a larger area than could be compassed by the apterous 

 insects. But this can be admitted only as a partial 

 explanation, and it does not answer why other fen- 

 species are not thus affected. 



Virgil's words, " Nimium ne crede colori," adapted 

 by Linn^us with reference to animals, may be well 

 pondered. Considerable diversity of colouring occurs 

 in the members of this group ; but non-pigmental 

 colour taken by itself, is not a safe guide. 



Again, important as are the characters of wing- 

 neuration, it is quite possible to come to wrong 

 conclusions through placing too much reliance upon 

 them. Independently of the aberrant forms, sometimes 

 met with, the substance of the elytra is often so horny 

 and opaque, that the veining cannot be made out with 

 precision. Although Scott uses both colour and markings 

 as helps to discrimination, he relies more on the 

 position of the pro-notal keels, and their prolongation 

 to the posterior pro-notal margin. As before stated, 

 attention to the genital styles, and a comparison with 

 the etched figures, given by Dr. Fieber, in ' Grunzuge 

 zur generischen Theilung der Delphaciden,' will give 

 material help in identifying foreign with British insects. 

 Dissection must be resorted to in all critical species. 



Until we know more of the life-histories, and can 

 gain sure points from breeding these small Cicadte, 

 we must be satisfied with such small and less 



