1922] Crampto7i — Relationship of Hemiptera-Homoptera 29- 



and Embiids apparenty sprang from the same source, it is very 

 probable that their common ancestors were very Hke the Pro- 

 torthoptera in many respects. 



That the fore wing of a Psocid could be readily derived from a 

 Protorthopteron prototype may be seen by comparing the fore 

 wing of the Psocid shown in Fig. 2 with that of the Protorthop- 

 teron shown in Fig. 4, since the venation of the two wings is 

 strikingly similar, and the Protorthopteron type is evidently 

 the more primitive one, since it is one of an older and lower 

 group, and the branching of the veins in general begins nearer 

 the base of the wing — which is usually a more primitive character 

 than for the branches to come off nearer the apex, since the latter 

 usually indicates a degree of coalescence, and hence a special- 

 ization, in the veins. The three anal veins are much alike in 

 Figs. 2 and 4, and the forking of the cubitus in the Protor- 

 thopteron shown in Fig. 4 (or better still in the Protorthopteron 

 shown in Fig. 26) is strikingly like that of the Psocid shown in 

 Fig. 2. The three branches of media, and the two branches of 

 Rs are also strikingly similar in the insects shown in Figs. 4 and 2, 

 and the nature of the first branch of radius and the subcostal 

 vein is much the same in both. The Psocids and Protorthoptera 

 thus apparently have many developmental tendencies in com- 

 mon, and probably inherited them from a common ancestry 

 which was very like certain Protorthoptera in may respects, 

 and as was mentioned above, the ancestors of the Zoraptera and 

 Embiids probably also resembled the Protorthoptera in many 

 respects. As will be shown in the next paragrpah, the Psocids 

 and Hemiptera-Homoptera have so much in common, that they 

 also in all probability were derived from the same type of an- 

 cestors which must likewise have resembled the Protorthoptera 

 in many respects, although the ancestors of the Homoptera in 

 all probability resembled the Protoblattids as well, and the 

 ''roots" of the Homopteron stem apparently strike somewhat 

 more deeply down into the Palseodictyopterous types. 



The peculiar bulging antefrontal region of the head incorrectly 

 called the "clypeus" in- Cicadid Homoptera and Psocids, the 

 peculiar lengthening of the segments of the antennae, which, so- 



