30 
Psyche 
[March 
as safe as any paleontologists — in concluding that the 
Mecoptera had reached their maximum during the Per- 
mian. The Neuroptera show a much more consistent series 
of figures during the Mesozoic and Tertiary, and it is doubt- 
ful in my mind that these percentages will change radically 
in the future. In this case, however, we see that the 
Neuroptera appear to make up a higher percentage of the 
Mesozoic fauna than the Permian one; but the difference 
is very slight, only a little over 1%, and since the Permian 
Neuroptera are quite as highly specialized as the Mecoptera 
of that period, it is very probable that a much larger num- 
ber of Neuroptera will turn up in new beds. The Odonata 
in both Mesozoic and Tertiary have been regular in their 
occurrence, so that there has been hardly any variation in 
their percentages during the past twenty years. Here the 
maximum seems to be in the Mesozoic, and the difference 
between the Permian on the one hand, and the Tertiary on 
the other is so great (even more so than in the Mecoptera) 
that it is extremely doubtful that this trend will ever be 
disturbed. The next order, the Psocoptera, has apparently 
had a history similar to that of the Mecoptera. While the 
percentages of these insects in the Mesozoic and Tertiary 
have varied somewhat, due to the early neglect of these 
small insects, they are so abundant in the Permian that 
there are no grounds for supposing that they will ever turn 
up in the Mesozoic and Tertiary to a similar extent. The 
Homoptera are the same. It should be noted that there 
was a great increase in the percentage of the Mesozoic 
Homoptera between 1908 and 1920, again, as in the case of 
the Psocids, because these minute insects were not observed 
in the deposits until after the publication of Handlirsch’s 
“Fossilen Insekten”. At the present time, although the per- 
centage of Mesozoic Homoptera is about 9% of the whole 
insect fauna of the period, it is very doubtful if this will 
ever increase to overtake the Permian ratio, where it is 
12.5%. When we come to the Coleoptera, we see that the 
percentage of these in the Mesozoic and Tertiary has been 
quite stable in collections obtained during the past 20 years. 
The striking fact, of course, is the evenness of their relative 
abundance as fossil from the Mesozoic to the present, es- 
pecially in contrast to the small percentage known in the 
