b CONTRIBUTIONS TO CANADIAN PAL^ONTOOGY. 



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

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

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

 the most bulky species, and even for these families they are exception- 

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

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

 Jassidae and the two species of Aphididse which are microtypic. The 

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

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

 them which are 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 well 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, Coelidia, 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, Sbenaphis, Palec- 

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

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

 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 1811 and 18 78 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 remarkable 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 Aphidinse. 



H 



