118 Psyche [June 



chamber. This is of a simple nature in the Psyllidffi. The fact 

 that this division separates the Cicadellida? and the Membracidffi 

 raises difficulties, as they are otherwise so closely related. It seems 

 improbable that such a condition arose in two or more groups 

 independently. It seems more probable that it has been lost in 

 two or more groups independently. Kershaw has shown that the 

 connection is fully developed in nymphs when hatched, so that it is 

 an embryonic character and not a later development to meet spe- 

 cial conditions. 



Judging by venation the Hemiptera must have divided into two 

 groups, the Homoptera and Heteroptera, early in the history of 

 the order, ])ut not early enough, in my opinion, to justify making 

 it into two orders. A very slight study of the venation of the 

 Homoptera shoM^s that the nearest approach to the hypothetical 

 ancestral type is not found among the Psyllidse but among the 

 Auchenorhynchi. 



A study of the hind legs also indicate a state of high specializa- 

 tion in the Psyllids. 



Again, in discussing the male genitalia of Homoptera, Dr. 

 Crampton has oflFended against his own advice. Although there 

 are several distinct types of both male and female genitalia among 

 the Auchenorhynchi he has selected Ormenis as the type to homo- 

 logize with other orders. But unless it can be shown that this 

 genus possesses a generalized type, any homologies drawn from ii 

 are of little phylogenetic value. 



Among the Cicadoidea we have two distinct types of male geni- 

 talia and a third in the Fulgoroidea. Cicadadae have no genital 

 styles or these are only rudimentary and are articulated and the 

 aedeagus comparatively simple. This is most likely specializa- 

 tion l)y reduction. In the other Cicadoidea there are two pairs of 

 appendages, the outer pair or plates and the inner pair. In some 

 forms the outer pair are amalgamated together and appear to be 

 part of the pygofer. In the Membracidfe the aedeagus is gener- 

 ally simple; in the Cercopidae it is often complex; in the Cica- 

 dellidffi it is of various forms, some of which are highly com pie v 

 and others greatly reduced. In the Fulgoroidea there is only one 

 pair of styles, which in certain cases are amalgamated into a 

 single organ. 



Both the inner styles of the Cicadoidea and the styles of the 



