1920] 



Crampton — Lines of Descent of Lower Winged Insects 



123 



lirsch considers as derived forms, rather than as primitive repre- 

 sentatives of the types ancestral to the saltatorial Orthopteroids. 

 Handhrsch, however, has reversed the evolutionary sequence in 

 other instances as well, since he would derive the anatomically and 

 enibryologically more primitive Dermaptera from Gryllidae, and 

 the fact that he derives the Hemimeridse (which are really a sub- 

 order of the Dermaptera) as a distinct offshoot of the Gryllidse, 

 would make it seem probable that he is not very familiar with the 

 anatomy of the insects in question. 



MECOPTER^- 



HYMENOPTERA 

 PSOCIDA-H0MOPTER& 



ZORAPTERA-ISOPTERA 



MANTIDA, 

 PROTOBLATTIDA, 



TRICHOPTERA 

 .NEUROPTERA 

 COLEOPTERA 

 DERMAPTERA 

 EMBIIDINA 

 PLECOPTERA 

 EPHEMERIDA 

 PALAEODICTYOPTERA 



Lines of descent of higher insects. 



In Fig. 5, are shown the interrelationships of the insects occupy- 

 ing a position near the base of the lines of descent of the higher 

 forms. The most important of these are the Zorapteron-Isopteron 

 group, and the Coleoptera with the Dermaptera, since the lines of 

 descent of the Zoraptera, the Hymenoptera and the Neuroptera 

 were derived from ancestors intermediate between these insects, 

 while the Psocidse, Hymenoptera and Neuroptera are in turn 

 intermediate between these insects and the higher forms such as 

 the Homoptera, Mecoptera, Trichoptera, etc. Thus, the Psocida 

 were evidently derived from ancestors extremely similar to the 

 Zoraptera,^ while the Psocida are in turn very like the ancestors 

 of the Homoptera (which gave rise to the Hemiptera). The 



1 As has been pointed out in a short paper soon to be published, the wing-veins of the Zorap- 

 tera are remarkably similar to those of certain Psocida Thysanoptera and Homoptera. 



