Haudliisch] „ . „ „ « • 



CANADIAN FOSSIL INSECTS 95 



Cretaceous; nevertheless in the early Tertiary they did not for a 

 long time attain that pre-eminence for which they were noted in the 

 late Tertiary, the Quaternary, and especially in recent times, where 

 they are distinctly dominant forms. In the early Tertiary they were 

 certainly also well represented in British Columbia ; and if they are 

 lacking in the collections, this fact must in part be attributed to 

 accident, and in part to their stiU meagre numerical development at 

 that time. Moreover, this datum may also be accepted as proof of 

 the relatively high age of the beds in question. A further argument, 

 of perhaps greater significance, rests on the relatively strong repre- 

 sentation of groups of Old-world forms: as the elaters, buprestids 

 (which were numerous even in the Lias) ; the pimplids, belonging to 

 the most primitive apocrite hymenoptersi; the cercopids, which are 

 also of Jurassic age ; also a form of Acrididse, which does not strictly 

 coincide with any of the recent subgroups; a rhaphidian in which 

 are found characters of both existing genera of this order, and 

 finally, a very primitive phyeopterid, the representative of a family 

 existing to-day in a few surviving forms. 



The Diptera clearly furnish the most reliable data. Of these 

 forms, the nemato'cerous Orthorrhapha with encephalous larvae; also 

 the above-mentioned phyeopterid, as well as the chironomids, myceto- 

 philids, and bibionids, have a relatively strong representation, and 

 outnumber all other dipters threefold; while, to-day, these condi- 

 tions are exactly reversed. The bibionids were especially prominent, 

 and appear to have formed the principal element of the fauna of that 

 time. They are exclusively represented by the genus Penthetria 

 (=PIecia), which throughout the world, at present, includes but few 

 more species than are comprised in the small collection under dis- 

 cussion. We shall, therefore, consider this group more carefully. 



Forty-one examples (including those of Sciidder) unquestionably 

 belong to the genus Penthetria, while 18 other imperfectly preserved 

 specimens — judging from their structure — ^may also be included here. 

 The number of species into which these 59 specimens are divided, 

 cannot be regarded as excessive if estimated at about 35 ; 20 species 

 having been determined from 30 very well-preserved examples. 

 Through the degeneration of one branch of the sector radii, the 

 closely allied genus Bibio is proved to be a form of later derivation, 

 which, however, appears to be entirely wanting. Which of these 

 genera is the older may be inferred from ttheir geological distribu- 



