96 CONTEIBUTIONS TO CANADIAN PALiEONTOLOGY 



tion in the European Tertiary; for there occur in the early Tertiary 

 Y3 species of Penthetria, with only 23 in the late Tertiary. Bibio, on 

 the other hand, has only 20 species in the early Tertiary, and 29 in 

 the late Tertiary. The latter genus has not been found in the 

 American Tertiary, and with the exception of the form from British 

 Columbia, mentioned by Scudder — ^which may well be separated into 

 several species — ^Penthetria has hitherto been represented by only one 

 other early Tertiary species. Only 36 recent species of Penthetria 

 are known, while of Bibio there are 95. The occurrence of so dispro- 

 portionately large a number of Penthetrias in the Tertiary of British 

 Columbia contemporaneous with the absence of Bibio also indicates 

 that the beds in question belong to the early Tertiary, and are at 

 least Oligocene in age. The supposition is obvious that the genus 

 Bibio originated in the East, probably in Europe, and later found its 

 way to North America, the present geographical distribution of these 

 two genera being about as follows: — 



Penthetria: Europe, 1; eastern Asia and Japan, 3; East India 

 and Malay Archipelago, 7; Australia, 5; South Africa, 1; North 

 America, 2 ; Central America, 8, and South America, 16 species. 



Bibio: Europe, 37; eastern Asia, 2; East India, etc., 3; Aus- 

 tralia, 6; Africa, 10; North America, 28; Central America, 7, and 

 South America, 8 species. 



From these figures it will be seen that Penthetria, to-day, exists 

 principally in tropical and sub-tropical countries; and in temperate 

 zones survives only in individual forms: one of these being the 

 single dwarf European species, Penthetria holosericea. Bibio, on the 

 contrary, is especially abundant in the temperate regions of North 

 America and Europe, but is sparingly represented in the south. So 

 much the more interesting, then, is the occurrence of such a large 

 series of fossil Penthetrias — ^the representatives of existing thermo- 

 philous forms — in a latitude so high as is the region of the Similka- 

 meen river. 



Not only in the Penthetrias, however, but also in Promastax, in 

 the numerous cercopids, and particularly in the huge Aphrophora 

 angusta mihi, Ricania, Scudder, etc., are found proofs of a warm 

 climate at that time. 



These data, therefore, taken together, lead to the safe conclusion 

 that the Similkameen deposits are, at least, Oligocene in age. 



