6 CONTRIBUTIONS TO CANADIAN PAL^EOX TOOiiY. 



But the most striking feature in the fauna is the size of ine indi- 

 viduals which compose it. Four fifths of the Horaoptera belong to the 

 families normally containing, except for the Cicadidae (Stridulantia), 

 the most bulky s])ecies, and even for these families they are exce))tion- 

 ally large or would class among the largest, while the two Ileteroptera 

 belong also to the larger types. It is only the single member of the 

 Jassidre and the two sjjccies of Aphididjc which are microtyijic. The 

 average length indeed of these tertiary species of Fulgoridai and Cer- 

 copidje is not less than two centimetres, and there are some among 

 them which ai'e probably double that length. 



From the insect data one can make no strong assertion regarding the 

 relative age of the deposits in which they occur, but there are one or 

 two points to which it may be Avell to direct attention. One is the 

 fact that nearly all the generic groups represented are so far as known 

 extinct ; even the few which are here placed in existing genera, — 

 Enchophora, Ricania, Ccelidia, Cercopis, Aphrophora,-^are in nearly 

 every case so placed only provisionally from the incompleteness of the 

 specimens found ; this would surely seem to indicate a relatively great 

 age, at least as old as the oligocene. Another is the reference of a 

 few, generally with certitude, to genera, — Gerancon, Sbeuaphis, Palec- 

 phora, Palaphrodes, — known otherwise only from American beds re- 

 ferred to the oligocene ; and besides these the only species elscAvhere 

 recorded is found likewise in the oligocene. The last fact, however, 

 looks in a different direction, for the cercopid element of the fauna, 

 and as we have seen its most important component, shows a distinct 

 resemblance to that of Radoboj in Croatia, which is regarded as mid- 

 dle miocene. 



HOMOPTERA. 



Family APHIDID^. 



In 187*7 and 1878 I described from the British Columbia tertiaries 

 two species of plant-lice, temporarily referring each to Lachnus. None 

 have since been added to them, but the study of a considerable series of 

 these insects from the American tertiaries shows a remarkal)le variety 

 of fossil forms and compels the establishment of a large number of 

 genera ; these two species are now found to fall into distinct and 

 extinct groups, each having one or two other representatives in the 

 American rocks. Both belong to the sub-family Aphidiuae. 



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