371 
[Scudder. 
1892. J 
phora, about eight hundred and fifty specimens having passed 
through my hands ; of these, however, fully a hundred have 
proved too imperfect for present use or until other specimens in 
better condition may show what they are. Seven hundred and 
fiftv-tbree specimens have served as the basis of a Monograph 
now printing and of the general remarks which here follow. 
More than half (431) of these specimens come from the single lo- 
cality of Florissant, Colo., and excepting a single specimen from 
Fossil, Wyo., and another from Scarboro, Ontario, the others 
are divided between three localities not widely removed : the 
crest of the Roan Mountains in western Colorado, the buttes on 
either side of the lower White River near the Colorado-Utah 
boundary, and the immediate vicinity of Green River City, 
Wyoming. 
One hundred and ninety-three species are determined, divided 
among ninety-five genera, thirty-six tribes or subfamilies, and six 
families, by which it will be seen at once that the fauna is a very 
varied one. It is richer than that of Europe, where there have 
been described (or merely indicated) only one hundred and fifty 
species of which nine come from the Pleistocene. Our older Ter- 
tiary rocks, therefore, are found to have already yielded nearly 
twenty-eight per cent more forms than the corresponding Euro- 
pean rocks. 
Although it is evident to any student of fossil insects that even 
in Tertiary deposits we possess but a mere fragment of the vast 
host which must have been entombed in the rocks, it is neverthe- 
less true that we have already discovered such a variety and 
abundance of forms as to make it clear that there has been but 
little important change in the insect fauna of the world since the 
beginning of the Tertiary epoch. In the earlier Tertiaries we 
not only possess in profusion representatives of every one of the 
orders of insects, but every dominating family type which exists 
today has been recognized in the rocks ; even many of the fami- 
lies which have but a meager representation today have also been 
discovered, and though many extinct genera have been recog- 
nized, no higher groups, with a single exception or two, have 
been founded upon extinct forms. This is one of the most strik- 
ing and prominent facts which confronts the student of fossil in- 
sects. It is the more striking from the delicacy, the tenuity, and 
minuteness of many of the forms which are here concerned ; and 
