INSECT EVOLUTION CHETVERIKOV. 445 



If we look at any table (as in Handlirsch) showing the inter- 

 relation and evolution of contemporary and fossil insects we will 

 see that almost all Paleozoic orders are extinct. We will also see that 

 the majority of them barely pass out of the Paleozoic period. But, 

 from the evolutionary point of view, the extinct orders are a direct 

 contrast to the majority of extinct orders of vertebrates. These latter 

 became extinct because in their specialization they had come to such 

 a pass from which there was no outlet. The Paleozoic orders of in- 

 sects, however, are all Proto orders {Protorthoptera, Protodonata, 

 Protohemiptera, etc.), and the most ancient order of this period is 

 Palaeodtctyoptera, an order which embodies in itself all the imagin- 

 able most primitive characters of a winged insect. 



These orders became extinct not because they were extremely 

 specialized, but because they evolved in the Mesozoic and gave rise to 

 more perfect, better adapted forms which replaced them. And thus 

 if we could get a glimpse into that world to see how these primitive 

 insects lived and how they looked it would help greatly to solve our 

 problem. 



If we were to turn to the authority on this subject, to the above- 

 mentioned Vienna savant, Anton Handlirsch, with the request to 

 picture to us the world of Paleozoic insects he could have hardly 

 answered us better than w T e find it stated in his comparatively recently 

 issued book on fossil insects. 1 This statement is so interesting that I 

 permit nryself to quote it in translation : 



To our eye, which is accustomed to see usually delicate and extremely 

 variable forms of insects around us, the character of the Paleozoic form of 

 insect fauna should appear very unusual. The vast majority of species of those 

 days exceeded by many times the dimensions of their contemporary progeny, 

 while small forms are entirely absent in the ancient formations, although, as 

 is evident from the Mesozoic deposits, they are capable of preservation not 

 worse than the large ones * * *. In the middle of the Upper Carboniferous 

 period the forest swamps of our areas were populated with cockroaches about 

 as long as a finger, dragon-fly-like creatures with a wing spread of about 2\ 

 feet, while insects that resemble our mayflies were as big as a hand. Heavy, 

 clumsy forms, adapted more for short flits rather than true flight, inhabited 

 the shores of streams and the forest clearings ; the ancestors of our grasshop- 

 pers, crickets, and cicadas, our flies, ants, and bees passed their monotonous, 

 cheerless life in deep silence, wholly devoted merely to the coarse question of 

 nourishment and the elementary functions of reproduction * * *. Only to- 

 ward the end of the Carboniferous period and later in course of the Permian 

 period, simultaneously with the dying out of the disappearing, primitive group 

 (Palaeodictyoptera) , do somewhat more highly organized forms appear and we 

 notice at the same time a diminution in their average dimension. 2 



A truly characteristic picture, not without some mystic greatness. 



In the accompanying illustration (pi. 1) we see a greatly (X4/7) 

 diminished restoration of one of the insect representatives of that 



1 Anton Handlirsch. — Die fossilen Insckten und die Phylogenie der recenten Formen. 

 Leipzig, 1906-1908. 



2 L. c, p. 1150; the italics are mine. 



