36 
Psyche 
[February 
another living insect belonging to a more primitive group; and 
on this account it is amazing that Mr. Muir should accuse me 
of deriving living Psyllids from living Psocids especially since 
I definitely state in a paragraph which he quotes, that the 
lines of descent of the Homoptera, Thysanoptera, Psocids 
Hymenoptera and related forms “apparently arose from an- 
cestors intermediate between the Zoraptera (with the Isoptera) 
on the one side, and the Coleoptera (with the Dermaptera) 
on the other.” In other words, the ancestors of the Homoptera, 
Psocida, Hymenoptera, etc., were very similar to the Prot- 
orthopteron-like and Protoblattid-like ancestors of the Zoraptera 
and Coleoptera. This is surely a very different matter from 
claiming that the Homoptera were descended from living Psocids! 
I have always been careful to state that the Psocids were in 
many respects very like the ancestors of the Homoptera, just as 
the chimpanzees are in many respects very like the ancestors of 
man (i.e. the Pithecanthropus - like forms), yet such a statement 
by no means implies that men were descended from living 
chimpanzees — and the same principle holds true in the com- 
parison of the Homoptera with the Psocids, abeit. the groups 
compared in the latter case belong to different orders instead of 
belonging to different families of the same order, and the differ- 
ences are naturally somewhat greater in the one instance than in 
the other. The idea which I intended to convey is that the 
Psocids and Homoptera are very closely related (i.e. they have 
both inherited many tendencies in common which cause their 
lines of development to parallel each other quite closely) and 
since the Psocids have evidently departed less than the Plomop- 
tera have from the common ancestral types, the ancestral 
features which they have preserved in a less modified condition, 
enable us to form some conception of the character of these 
features in the ancestors of the Homoptera. 
Starting with the false assumption that I would derive living 
Homoptera from living Psocids (an obvious impossibility), 
Mr. Muir proceeds to a second equally false assumption that I 
would derive all Homoptera from living Psocids by way of the 
highly specialized recent family Psyllidse, simply because I 
