38 TERTIARY INSECTS OF NORTH AMERICA. 



an exquisite state of preservation. Vegetable remains, excepting of a very 

 fragmentary nature, were rare, and most of the insects, like those obtained 

 by Denton, of a small size; excepting, indeed, dipterous larva?, which were 

 found in quite incredible numbers, square rods of stone near the higher 

 levels being absolutely covered with them in multitudes of places. 



The insects obtained by Mr. Denton and Dr. White at these localities are 

 all included in the present volume, but no reference is made to those found 

 by myself in 1889. The age of the deposit can hardly be said to be as yet 

 determined, but the leaves found by Mr. Denton (presumably at "Fossil 

 Canon") were regarded by Mr. Lesquereux as more certainly synchronous 

 with those of Florissant than with those of the Green River beds, and in 

 any event all three are of very nearly the same age. 



Green River, Wyoming. All the insects described in this volume from 

 Green River were obtained at a single spot, next what is known as the Fish- 

 Cut, where the railway cuts through the rocks, about three or four kilome- 

 ters west of the crossing of Green River. Even here they have been found 

 only within the compass of one or two square meters of ground, and by 

 repeated visits this " pocket" has now been entirely chipped away. There 

 is no doubt that other equally prolific pockets will be found in the same 

 immediate vicinity, especially in the more favorable exposures east of the 

 river, as one such was found during the summer of 1889. It is by no means 

 improbable that the beds at this locality and those at White River may 

 prove to belong to the floor of one and the same Tertiary lake to which 

 King gave the name of Gosiute Lake. About one hundred and fifty 

 different insects have been found here, besides many others not yet described. 

 They are most commonly Coleoptera, this order being represented by fully 

 one-third of the species. Hemiptera and Diptera come next with almost 

 equal representation, or about twenty-three per cent each. Next come the 

 Hymnoptera with eight per cent. The other orders are about equally and 

 meagerly represented, the Lepidoptera not at all. 



Fo.s.s/7, ]}'//<))>iitj. A few species of insects have been found in the 

 bluffs facing the town of Fossil at the head of Twin Creek, a tributary of 

 Bear River, bluffs which are famous for the immense number of fossil fish 

 they have furnished. As a rule the insects are scarce, and, like the fish, 

 belong to a very limited number of species, in this case mostly Coleoptera 

 and Diptera. In the present work only two or three are mentioned. 



