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, Thysanoptcra, 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 Homop- 

 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 

 liighly specialized recent family Psyllidse, simply because I 



