16 
Psyche 
[March 
including such groups as the Paleodictyoptera, the Blat- 
taria, the Megasecoptera, etc. In marked contrast to this, 
the Permian has unexpectedly furnished us with a remark- 
able series of specimens, representing groups which have 
not previously been reported from this horizon. In 1920 
Handlirsch listed from the Permian 97 species of insects, 
aside from cockroaches; now there over 250, also exclusive 
of cockroaches, and many additional species are contained 
in unworked collections recently obtained from Permian 
deposits. For the most part, these new fossils have been 
secured at three widely separated localities, in Australia, 
North Russia, and Kansas. The Australian and Kansan 
specimens have almost exclusively been studied by Tillyard, 
while the Russian material has been investigated by Mar- 
tynov. Of course such fossils have thrown much light on 
the geological ranges and the phylogenetic origin of our 
existing groups of insects. We now know that many recent 
orders had a much longer geological history than had been 
supposed; for the first time the Mecoptera, Neuroptera, 
Coleoptera, Diptera, Odonata, Homoptera, Psocoptera, and 
Orthoptera 3 have been found in the Paleozoic. 
The Mesozoic has likewise contributed much to our col- 
lections during the past decade. The Triassic, which had 
previously been nearly a blank as far as insects were con- 
cerned, is now represented by about 120 species, described 
by Tillyard from Queensland. Martynov has published on 
another remarkable series from the Jurassic of Turkestan, 
and his studies are by no means complete. Mention should 
also be made of Tillyard’s monograph of the Liassic dragon- 
flies of England, and Ping's study of the Cretaceous insects 
of China. The latter work is particularly interesting since 
it has brought to light the only promising insect deposit 
of the Cretaceous which has yet been found. 
The Tertiary, of course, has played a large part in the 
recent advances of insect paleontology. The Baltic amber 
insects have received much attention at the hands of several 
specialists; certain groups, as the Thysanura, Colembola, 
and Paussidae, have been completely revised. Cockerell has 
continued his description of the Florissant and Green River 
3 Undescribed. 
