■-28 Psyche [Febru 



ary 



Psocids such as Embidopsocus, for example, suggests a very close 

 relationship between the Psocids and Embiids, and since the 

 Psocids were apparently derived from Protorthoptera-like 

 ancestors (as will be presently discussed) it is to be expected 

 that their near relatives, the Embiids, would also be derived from 

 Protorthoptera-like ancestors, so that in indicating an ancestry 

 for the Embiids anatomically intermediate b3tween the Haden- 

 tomoids and Protorthoptera, the evidence of the wing venation 

 is quite in harmony with that from other sources as well. 



The venation of the Psocid wing shown in Fig. 1 is so similar 

 to that of the Zorapteron shown in Fig. 3, that both were evident- 

 ly derived from the same source, and what applies to one applies 

 to the other as well. The Psocid and Zorapteron wings shown 

 in Figs. 3 and 1 could readily be derived from the Embiid type 

 of fore wing shown in Fig 7 (as is indicated in the hypothetical 

 intermediate condition shown in Fig. 5) * in the following way. 

 The second branch of cubitus of Fig. 7 might become more verti- 

 cal, while vein M, which arises from M + Cu and coalesces for a 

 short distance with Rs. in Fig. 7, might unite with Rs further 

 from the base of the wing thus lengthening that portion of M 

 which extends between M + Cu and Rs, as in Fig. 3. R2-|-3 of 

 the radial sector, Rs, bends upward toward Ri in Fig. 7, and if 

 R4-I-5 wereto unite with it to form a single branched Rs bending 

 forward to meet Ri, the condition exhibited by Rs in Fig. 3 

 would be produced. A deposition of chitin and pigment in the 

 space between Sc and Ri (as indicated in Fig. 5) would produce 

 a pterostigma such as the one labeled "ps" in Figs. 1 and 3. 

 Judging from the same developmental tendencies found in the 

 Psocids, Zoraptera, and Embiids, it would appear that all three 

 were derived from a common ancestral source, and many of the 

 genes, determinants, or factors occurring in this common source 

 were inherited by the three derived groups, although they were 

 naturally slightly modified by other factors in the derived 

 groups, as would be expected. As is pointed out in the next 

 paragraph, the ancestors of the Psocids were apparently very 

 similar to the Protoi-thoptera, and since the Psocids, Zoraptera 



*The figure in the left hand column between Figs. 3 and 7 is Fig 5. The label was lost 

 from this figure, having been pasted on too insecurely. 



