1947] 
Early Insect Life 
85 
mentary, their identification is substantiated by the pres- 
ence of more definite specimens in late Permian rocks of 
Australia. The latter were considered by Tillyard as 
being very closely related to the existing Eustheniidae 
of the Australian region. The Tbysanoptera or thrips, 
also found in Russian deposits, are of course minute and 
the details of the wings are not known; but the fossils 
certainly show the general characteristics of the tlirips. 
The first unquestionable Coleoptera, or beetles, are 
found in the Upper Permian of Russia and Australia. Un- 
fortunately, complete specimens are unknown, though sev- 
eral well preserved elytra have been found. The family 
relationships of the fossils cannot be ascertained on these 
structures alone ; but several types of elytra are repre- 
sented, including some which are alike those of the Cu- 
pedidae, and others which recall those of the Hydrophilidae. 
It should be noted that since beetles are very abundant in 
Triassic deposits, their presence in the Permian is not 
surprising. 
This then, is a general picture of early insect life. Our 
knowledge of it is limited, and there are many gaps to he 
filled, but we do have some idea of its nature. In reality, 
two faunas existed during the geologic periods consid- 
ered — a Carboniferous fauna and a Permian one. The 
contrast between these two is fully as great as that be- 
tween the faunas of the Triassic and the present. Even 
by late Permian time, about one-third of all the living 
orders of insects had come into existence, and the abrupt 
appearance of so many existing orders in the Lower Per- 
mian suggests that some of them lived in Carboniferous 
time, though not yet found in strata of that period. This 
early insect fauna included both predators and plant 
feeders, some of which had suctorial mouth-parts. The 
metamorphosis of the Carboniferous species, so far as 
known, was of the incomplete type, some apparently 
having aquatic nymphs ; but by early Permian time, com- 
plete metamorphosis had been acquired. All of this took 
place before the existence of flowers or mammals or 
birds — to say nothing of man. It is no wonder that the 
insects have such a tenacious hold on what we consider 
to be our planet. 
