PREFACE. 
When, in January, 1886, the Division of Fossil Insects of the U. 8. 
Geological Survey was established, and I entered upon my duties therein, 
I had still on hand in an incomplete condition a report upon our Tertiary 
insects for the U. S. Geological Survey of the Territories, under Dr. F. V. 
Hayden, the plates for which were already finished. This work, which 
was completed early in 1890, contained a full account of all the Tertiary 
insects of our country known up to within a few years, as far as regarded 
the lower orders; but the higher orders, and especially the Coleoptera, 
Diptera, and Hymenoptera, which comprised those richest in material, were 
left nearly untouched, only the earlier found specimens in the Green river 
beds, and which had already been engraved on the plates, being included, 
leaving the far richer fauna of Florissant, Colorado, entirely untouched. 
The elaboration of this immense amount of material, enlarged by 
additions from other localities, including some new and rich, was begun 
immediately upon the completion of the Hayden report, and the present 
work is a first instalment toward a history of our fossil Coleoptera. In 
the division treated are included 193 species, all but one of which come from 
the older Tertiaries, while there have been described (or merely indicated) 
from the European Tertiary rocks only 150 species, of which 9 come from 
the Pleistocene. Our older Tertiary rocks, therefore, are found to have 
already yielded nearly 28 per cent more forms than the corresponding 
European beds. It is altogether probable, such is the extent and richness 
of the fresh-water Tertiary deposits of the West, that this proportion will 
be largely increased in the future, particularly as the exploitation of our 
Tertiary insect deposits has been merely begun; the number of persons 
who have been engaged in any field-work upon them, may be counted 
upon one’s fingers, and no natu ralist besides myself has yet undertaken 
their study. 
