PROC. EXT. SOC. \VASH., VOL. 22, XO. 5, MAY, IQ2O 103 



and Embiidae among the lower forms, although the nota of the 

 wingless Zoraptera are strikingly like those of a wingless (,'ryllo- 

 blatta. While the coxae are like those of the Grylloblattidae, the 

 legs in general resemble those of certain wingless Psocidae and 

 immature Plecoptera. The genitalia of the apterous males are 

 as much like those of male Mantidae as any other insects, although 

 they will doubtless prove to be quite similar to the genitalia of a 

 male (,'rvlloblatta also. The terminal segments of the males bear 

 certain structures somewhat similar to those of certain Plecoptera; 

 but the terminal segments in general, and those of the winged 

 females in particular, are quite Isopteroid. 



The following diagram will serve to locate the line of descent of the Zor- 

 aptera among those of the other lower winged insects. 



PSOCIDS. 



ZORAPTERA \ DERMAPTERA 



ISOPTERA\ i / EMBIIDS 



PLECOPTERA 



MANTIDS 

 GRYLLOBLATTIDS 



Taking their anatomy as a whole, I would regard the Zoraptera 

 as intermediate between the Isoptera and the Plecoptera, with 

 their closest affinities tending slightly toward the side of the 

 Isoptera, although the balance of characters is so evenly divided 

 between the two groups, that it is very difficult to decide whether 

 the Isoptera or the Plecoptera are the nearest relatives of the 

 Zoraptera. There can be no doubt, however, that the Plecoptera 

 are extremely close to the forms from which the Zoraptera were 

 derived, and represent as nearly as any living insects, the com- 

 mon ancestral type of insects giving rise to the lines of descent 

 of the Zoraptera and Isoptera. On the other hand, the Zoraptera 

 themselves are very like the ancestors of the Psocidae, so that 

 they are extremely important insects for a study of the evolution 

 of the higher forms such as the Hymenoptera, N'europtera, etc., 

 whose ancestors were undoubtedly extremely colsely related to 

 those of the Psocids. The position of the Zoraptera in the super- 

 orders of winged insects, may be seen in the following list. 



