Scudder.J 
378 
[Jan. 20t 
Now when we come to examine the species of Rhynchophora, 
we shall find that while the three localities in western Colorado 
and Wyoming share a number of forms in common, not a single 
species found at Florissant occurs in either of the others. To 
give the precise figures : from Florissant one hundred and sixteen 
species have been obtained ; from the Roan Mountains, forty, of 
which it shares six with Green River, and seven with White 
River besides six others common to all three localities, together 
nearly half its fauna (19 sp.) ; from the White River twenty-three 
species, of which it shares two with Green River and seven with 
Roan Mountains besides the six common to all, or nearly two 
thirds its fauna (15 sp.) ; and from Green River thirty-nine spe- 
cies, of which it shares two with White River and six with the 
Roan Mountains besides the six common to all, or more than one 
third its fauna (14 sp.). These facts with the field evidence ap- 
pear to show that the three principal localities in western Colorado 
and Wyoming are deposits in a single body of water, the ancient 
Gosiute Lake, as it was called by King. The absolute separation 
in specific forms between the fauna of these deposits and that of 
Florissant must be indicative of a distinction greater than that of 
mere geographical position, for the Roan Mountains are about 
equally distant from Green River and Florissant. It is clearly an 
indication of a difference in age, though they have usually been 
regarded as occupying similar horizons. In the Monograph de- 
scribing these forms I have referred to the species regarded as 
belonging to the Gosiute Lake as the Gosiute fauna whenever it 
has been desirable to speak of them in common ; and in contrast 
I have called the fauna of Florissant, the Florissant or Lacustrine 
fauna. Which of them is the older cannot be determined until 
their faunas have been more completely studied ; and even then 
for lack of sufficient comparisons elsewhere on the continent, it 
may be impossible from the insect-remains alone to reach any pos- 
itive conclusions. When the structure of the Green River beds 
has been more completely studied, their age can doubtless be de- 
termined with much accuracy ; and a similar result may be 
reached when the age of the orographic movement shall have 
been determined which brought about the emptying and desicca- 
tion of the ancient Florissant Lake. With these time elements 
given, the extent of the insect-remains in the Gosiute and Lacus- 
trine faunas is such that the relations of deposits hereafter dis- 
covered may be quickly made clear. 
