136 ENTOMOLOGICAL NEWS [xxxii, '21 



highly modified. Thus, in the fossil insect Eugereon, which 

 some investigators consider as representing the type ancestral 

 to the Hemipteroid insects, the wings are still in the primitive 

 stage of development represented by the Palaeodictyoptera, 

 while the mouthparts have become as greatly modified as those 

 of the highly specialized parasites forming the order Siphon- 

 aptera, or the fleas. In fact, the labial palpi, hypopharynx, 

 etc., of Eugereon arc remarkably similar to those of the fleas 

 (as well as those of the Neuropteroids related to the fleas, 

 such as the Diptera, Mecoptera, Neuroptera, etc.) and the 

 mouthparts of Eugereon are so similar to these forms, rather 

 than the Hemipteroid insects, that it would hardly seem that 

 Eugereon stands in the direct line of descent of the Hemip- 

 teroid insects, and in fact it is no nearer to them than the 

 rest of the Neuropteroids are. At any rate, Eugereon furnishes 

 us with an example of an insect in which the wing veins have 

 remained practically unchanged from the. ancient Palaeodicty- 

 opteron type, while the mouthparts have become as greatly 

 modified as those of the highly specialized order Siphonaptera. 

 On the other hand, the head of the Zoraptera is very much 

 like that of the primitive order Plecoptera, while the wings 

 of the Zoraptera have become so highly modified that they 

 approach the types found in the Homoptera. On this account, 

 if we were to regard the wing venation alone in these insects, 

 we would not be able to fit them into their proper places in 

 the developmental series as accurately as we are able to do by 

 taking into consideration all of the features of the body, etc., 

 and whatever evidence is available from all other sources 

 ( t'. g., embryology, etc.) as well. I would therefore treat 

 the evidence of relationship furnished by the wing veins as 

 merely a part of the whole evidence, and until it is sup- 

 ported by evidence from other sources as well, I would give it 

 no greater weight than that furnished by the study of any 

 other single set of structures. On the other hand it must be 

 admitted that it would be perfectly possible to trace the 

 origin and development of all of the lines of descent of the 

 insectan orders by using one set of structures alone such as 

 the evolution of the antennae, legs, mouthparts, etc., pro- 



