94 Annals Entomological Society of America  [Vol. XIV, 
indicates a close relationship between the Coleoptera and the Der- 
maptera. On the other hand, the occurrence in coleopterous and 
neuropterous larvee of the peculiar type of maxilla with both palp, 
“mp,” and slender galea, ‘“‘ga,’’ borne on a slender segment-like 
structure, ‘‘ds,”’ (see Figs. 23 and 27) in addition to other features of 
resemblance in the larvze of the two groups (e. g., nature of the thoracic 
sclerites, etc.), indicates a close relationship between the Coleoptera 
and the Neuroptera. In fact, it is extremely difficult to discover any 
features which will distinguish a larval Coleopteron from a larval 
Neuropteron in every case, and certain coleopterous larve might 
readily be mistaken for neuropterous larvae, so great is the similarity 
between the two groups. The Coleoptera, however, are the more 
primitive of the two orders (Neuroptera and Coleoptera) and serve to 
connect the Neuroptera with the insects related to the Dermaptera 
on the one side and with those related to the Isoptera (with the Zorap- 
tera) on the other. In some respects, the Coleoptera are very like the 
Embiide, particularly in the nature of the head capsule and certain of 
the mouthparts, as may be seen by comparing Fig. 17 of a beetle with 
Fig. 18 of an embiid; and the “‘roots’’ of the Coleopteron line of develop- 
ment strike down deeply into the group of insects related to the 
Dermaptera (i. e., the Embiidze and Plecoptera), some of the coleopterous 
features being even more primitive than these features in the Dermaptera 
although the Dermaptera as a whole are much more primitive than the 
Coleoptera. 
The head region of certain Psocide (sensu lato) is very like that of 
some of the Neuroptera (and Hymenoptera also), particularly in the 
frontal region of the head. The fact that the head region of some 
Hemiptera (Corixide, etc.) overlaps the pronotum is a feature indicating 
a relationship to the Psocide, when taken in conjunction with other 
resemblances in the head capsule of the two groups (Hemiptera and 
Psocidze). The type of head found in the Psocide was apparently 
derived from the Zorapteron type, which in turn was derived from a 
Plecopteron type (although the Zoraptera are undcubtedly related to 
the Isoptera as well). From the morphological standpoint alone, the line 
of development of the Hemiptera would therefore be suggested by the 
series Plecoptera, Zoraptera, Psocide, Homoptera (the Psyllidze 
approach the Psocidz in many respects) and Hemiptera. The Thysan- 
optera also approach the Psocidz in many respects, and I have found 
a psocid whose head is very suggestive of the type leading to the 
Thysanopteron type, as will be brought out in a later publication. 
Not only does the typical psocid head approach the Neuropteron 
type in many respects, but the head of a sawfly also resembles both 
of these types very markedly and the evidence offered by a study of 
the head structures is quite in accord with the former contention 
(Crampton, 1920) that the Hymenoptera are anatomically intermedi- 
ate between the Psocidee and the Neuroptera. 
