84 
Psyche 
[June 
dentally, the early Mesozoic, the Mecoptera were rela- 
tively abundant and diverse. In one Permian deposit in 
Russia the Mecoptera make up 20% of the insect fauna 
found there, though at the present time they comprise less 
than .05% of the world’s insect fauna. The Neuroptera 
of the Permian are no less interesting than the scorpion- 
flies. Two distinct types occur in Lower Permian rocks — 
the Rapliidiodea or snake-flies, and the Planipennia. Very 
little is known of their body structure, but their wings 
indicate that, whereas the Lower Permian snake-flies were 
primitive and closely related to existing families, the 
Figure 9. Agetocliorista tillyardi Martynov (Order Mecoptera), from the 
Upper Permian of Russia. (After Martynov.) 
Planipennia were highly specialized, and only remotely 
related to existing groups. In Upper Permian rocks, 
however, the Planipennia are represented by an extensive 
series of fossils which are close to certain living families, 
such as the Berothidse, Sisyridae, etc. 
There remain to be considered now three other orders, 
two of which, the Tliysanoptera and Perlaria, appear first 
in Middle Permian rocks, and the third, Coleoptera, in 
late Permian deposits. The earliest Perlaria have been 
found in Russian strata and although they are very frag- 
