32 
Psyche 
[February 
ing parallel to the margin (but at some distance from it) in the 
fore wing. The nature of the thoracic sclerites of the Homop- 
tera would lend further weight to the view that the ancestors 
of the Homoptera were very like those of the Neuroptera, and 
the fact that many insects descended from the common Neurop- 
teroid stem, such as the Mecoptera (and even the Siphonaptera) 
exhibit very similar tendencies in the specialization of their 
mouth-parts (which tend to lose the ligula, while the labial palpi 
become approximated and unite to some extent, and the maxil- 
lae become much elongate and somewhat stilet-like) would suggest 
that they and the Homoptera inherited these tendencies from 
a common ancestry. Furthermore, the fore wings of certain 
primitive Trichoptera and Mecoptera, which were derived from 
a common Neuropteroid stem, show undoubted affinities with 
certain types of Homopterous fore wings, and lend further 
weight to the supposition that the ancestors of the Homoptera 
resembled those of the Neuropteroid insects in many respects. 
Thus, the Trichopterous fore wing shown in Fig. 27 is remarkably 
like that of the Homopteron shown in Fig. 29, especially in the 
character of the anal and cubital veins; and the other veins of the 
wing are also of much the same type in the two wings under con- 
sideration. All of these facts, which indicate that the ancestors 
of the Homoptera and Neuroptera were very closely related, 
are in harmony with the fact that the Homoptera and Psocids 
are also very closely related, since the Psocids themselves are 
clearly related to the Neuroptera, and their line of development 
apparently merges with that of the Neuroptera near its point 
of origin, thereby involving the line of develpoment of the 
Homoptera with that of the Neuroptera through their mutual 
relationship to the Psocids, as well as through the more direct 
affinities of the Homoptera themselves with the Neuropteroid 
insects. I have therefore maintained that the ancestors of the 
Homoptera were intermediate between those of the Psocids and 
those of the Neuroptera, and the present study of the fore wing 
venation would uphold the correctness of this view. 
If one compares the wing of a Neuropteron such as the one 
shown in Fig. 34, with the wing of a Protoblattid such as the one 
