292 GEOLOGICAL SURVEY OF THE TERRITORIES. 
warmer climate than now—a climate which may, perhaps, best be com- 
pared to the middle zone of our Southern States. The known living 
species of the genera to which they belong are in general credited to re- 
gions like Georgia in this country and the two shores of the Mediter- 
ranean in Europe. The presence of species of Theridium, Linyphia, 
Tethneus, and Epeira, including two-fifths of the species, has no special 
significance; but Thomisus, Segestria, Clubiona, Anythaena, and Tita- 
noeca, and especially Parattus, Tetragnatha, and Nephila, certainly pre- 
sent an ensemble, the indications of which cannot be overlooked. White 
ants are essentially a tropical family, only one or two out of eighty 
known species occurring north of latitude 40°. In North America only 
three have been recorded north of the border of the Gulf of Mexico, ex- 
cepting on the Pacific coast, where one or two more extend as far as 
San Francisco. Two species, both belonging to the second section, are 
found in the valleys below Florissant, in 39° north latitude. Florissant 
itself is situated 2,500 meters above the sea, and the presence of so con- 
siderable a number of white ants imbedded in its shales is indicative of 
a much warmer climate at the time of their entombment than the locality 
now enjoys. So, too, the occurrence among other Neuroptera, of Raphi- 
dia and Inocellia, of Lithagrion, and probably of the peculiar forms of 
Agrion, bears similar testimony; and the discovery of so many genera 
represented in or allied to those found in the Prussian amber is also in- 
dicative of a much warmer climate, since the amber fauna itself is held 
to show, for that period and place, a climate not far removed from that 
of the two borders of the Mediterranean. Investigation of other forms 
increases the weight of this evidence at every step, for nearly all the 
species (very few, certainly, as yet) which have been carefully studied 
are found to be tropical or subtropical in nature. As, however, a large 
proportion of those studied have been selected for some striking feature, 
too much weight should not -be given to this evidence. 
As noted above, the superabundance of specimens of single species 
of plants (Planera and Myrica) is repeated in the insects, where certain 
species of Formicidae among Hymenoptera, of Bibionidae among Dip- 
tera, of Cercopida and of Alydina among Hemiptera are to be counted 
by fifties and hundreds. 
The only other general feature which may already be noted among 
the insects is an unexpected paucity of aquatic larvae or the imagos of 
water-insects. Hardly a dozen neuropterous larvae have come to hand, 
very few aquatic Hemiptera in any stage, and of Hydrophilidae and other 
water-beetles no great number. The paucity of neuropterous larvae is 
the more remarkable from the abundance of Phryganidae, while not a 
single larva-case has been found. 
As to the age of these deposits, the opinions of Mr. Lesquereux, based 
on the study of tertiary plants, and of Professor Cope, drawn from his 
knowledge of tertiary fishes, are far more harmonious than one would 
expect from their known divergence of view concerning the testimony 
of the fossils to the age of other tertiary beds in the West. Such dis- 
parity of ideas did hold at first, Mr. Lesquereux maintaining in his ear- 
lier notices of the flora the probability of its later miocene age; in the 
Tertiary Flora he placed it in the “Upper Green River ” division of his 
“fourth group,” together with the flora of Elko, Nev., the Green River 
beds being placed directly beneath them. In Hayden’s report for 1876 
he refers the Florissant deposits to the upper miocene. In his review 
of Saporta’s Monde des Plantes,* while still considering it as miocene, 
he points out certain important relations which it bears to the flora of 
*Am., Journ. Se. (3), xvii, 279. (1879.) 
