ix] PAST AND PRESENT 107 



that of its nearest living allies. And all the fossil 

 insects known can be either referred to existing 

 orders, or shown to indicate definite relationship to 

 some existing group. 



Passing over some doubtful remains of Silurian 

 age, we find in rocks usually regarded as Devonian 1 

 the most ancient fossils that can be certainly referred 

 to the insects, while from beds of the succeeding 

 Carboniferous period, a number of insect remains 

 have been disinterred. These Palaeozoic insects 

 were frequently of large size, and they show distinct 

 affinities with our recent may-flies, dragon-flies, stone- 

 flies, and cockroaches. In the Permian period, the 

 latest of the divisions of the Palaeozoic, lived Euge- 

 reon, an insect with hemipteroid jaws and orthopteroid 

 wings. All these insects must have been exopterygote 

 in their life-history, if we may trust the indications of 

 affinity furnished by their structure. In the Mesozoic 

 period, however, insects with complete transforma- 

 tions must have been fairly abundant. Rocks of 

 Triassic age have yielded beetles and lacewing-flies, 

 while from among Jurassic fossils specimens have 

 been described as representing most of our existing 

 orders, including Lepidoptera, Hymenoptera and Di- 

 ptera. In Cainozoic rocks fossil insects of nearly six 

 thousand species have been found, which are easily 



1 The ' Little River' beds of St John, New Brunswick, Canada, by 

 some modern geologists however considered as Carboniferou?. 



