192 BRITISH CICAD.^. 



of a species. Facts like these are difficult to reconcile 

 with a protective theory, except by somewhat com- 

 plicated arguments which require certain assumptions. 



GrENERAL KeMARKS UPON THE DISTRIBUTION AND 



Habitats of Tettigid^. 



The flora and fauna of a district obviously must 

 have a biological connection between them, for one 

 forms the chief food of the other. Some Cicadae are 

 confined to certain localities from the circumstance 

 that their peculiar food-plants there flourish. It is 

 not, however, safe distinctively to name insects from 

 the particular character of their food ; for altered 

 circumstances sometimes compel changes, which may 

 make such specific names misleading. As an illustra- 

 tion, Aphrophora aim may be abundantly taken on Viola 

 canina, Buhus fnicticosus, Vesicaria rubra, and even Pinus 

 sylvestris, as well as on Alnus glutinosus. Fhilcenus 

 spumarius of the allied genus will blow up its froth on 

 almost any leaf sufficiently succulent. 



Dr. J. Sahlberg, at the commencement of his 

 'Ofversigt,' ranges the Cicadariye under heads, showing 

 different localities, . but this is chiefly for the con- 

 venience of searching for the live insects. Amongst 

 these habitats the following grouping wall be worthy of 

 notice, since it relates either to local species or to those 

 of less common occurrence in this country : — 



Pine trees and firs (Pincta). Eiiptcrijx Germari, 

 Tijphlocyba rosce, T. 10-punctata, Thamnotettix ahietina, 

 Z'ljgina hlandula. 



Woods (Kemora). Leclra aurita. 



High hills (Alpes). Thamnotettix torneella, Stiroma 

 alhosignata, Limotettix Q-jnmctata, Euacanthus interruptus. 



Sandy shores {Litora arenosa). Deltocephalus sahidieola. 



Marshes {Paludes). Olearus leporimis, Delphax pid- 

 chellus, Paramcsiis phragmitis, Lihwiiia longipennis. 



