1938] 
Fossil Insects 
107 
flying over the water were of course caught and entombed 
by the ash. 
Knowlton’s study of the Creede plants led him to conclude 
that the Creede formation was about the same age as the 
Florissant deposit, i.e., upper Miocene. At the same time, 
however, he noticed an obvious difference in the composition 
of the two floras, the most abundant element in the Creede 
flora being Coniferae, which, although very rare at Floris- 
sant, comprised about a third of the species and nearly a 
half of the individual specimens. The general content of 
the Creede flora strongly indicates that the lake-bed was 
deposited at a considerable higher elevation than the Floris- 
sant shales. 1 As Cockerell has stated of the Creede flora, 
very few, if any, high altitude insect faunas have been pre- 
served. The chief importance of the Creede specimens, 
therefore, depends not so much on their geologic age as on 
the environment in which they existed. It is of course far 
too soon to say anything definite about the biotic indications 
of the Creede insects, but even a cursory survey of the col- 
lection at hand, made during the sorting of the specimens 
into families, indicates that the fauna is an exceedingly 
small one, there being an extraordinary duplication of a few 
species. This is of course typical of existing faunas at high 
altitudes. 
Order Neuroptera 
Family Chrysopid^] 
By F. M. Carpenter 
Eleven specimens of this family are contained in the col- 
lection from Creede. This is proportionally a much greater 
number than has been found in the Florissant shales, which 
have produced only about the same number in a total of 
approximately 40,000 specimens. Two species are repre- 
sented in the Creede series, one apparently being identical 
with a Florissant species, and the other, already described, 
being peculiar to the Creede formation. The phylogenetic 
significance of the Tertiary Chrysopidae has already been 
discussed in an earlier paper (1935). 
x At the present time, however, both lake deposits have an elevation 
of about 8200 ft. 
