Vol. XXVl] ENTOMOLOGICAL NEWS 341 



extended study is impossible, from lack of material). Before 

 attempting to point out the relationship of the Grylloblattidae 

 to the neighboring groups of insects, however, it will be nec- 

 essary to briefly discuss the systematic position of these re- 

 lated groups, in order to more readily appreciate the meaning 

 of the mutual resemblances of several of these groups, and to 

 realize the significance of the combination of characters found 

 in the annectent Grylloblattidae. 



The two groups of pterygote insects which seem to have de- 

 parted the least from the ancestral type, are the Plecoptera and 

 the Blattidae. Certain Plecoptera nymphs are strikingly sim- 

 ilar to the Lepismatidae, not only in their general "habitus," 

 but also in various morphological details, such as the structure 

 of the antennae, mouthparts, prothoracic sclerites, etc.; and 

 in the same way, the Blattidae are strikingly similar to the 

 Lepismatidae. Indeed, the resemblances between these imma- 

 ture Plecoptera (or the Blattidae) and the Lepismatidae are 

 far greater than those between the Plecoptera (or Blattidae) 

 and the higher pterygote insects such as the Diptera, Lepidop- 

 tera, etc. It would therefore appear to be very probable that 

 the Plecoptera, Blattidae, and Lepismatidae (i. e. Lepisma, 

 Nicoletia, etc.), are closely related, and doubtless sprang from 

 very similar ancestors ( i. e. from ancestors which would doubt- 

 less have been grouped into a single order, or possibly a single 

 family). 



Very closely related to the Plecoptera, on the one side, are 

 the Embiidae ; while on the other, the Plecopteron line of de- 

 velopment is very closely paralleled by that of the Dermaptera. 

 Indeed, such forms as Ari.rcnia (specimens of which were kind- 

 ly loaned me by Dr. K. Jordan), combine in themselves char- 

 acters found in both Plecoptera and Dermaptera, and the im- 

 mature stages of such Dermaptera as Dyscritina, Karschiella, 

 Boniiansia, etc., in which the forceps are preceded by Plecop- 

 teron-like cerci, serve to connect the Plecoptera and Dermap- 

 tera or rather, they indicate a common origin for the two 

 lines of descent. 



