Vol. XXviJ ENTOMOLOGICAL NEWS 34I 



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

 'ng to point out the relationship of the GrjUoblattidae 

 I icighborinjj 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 Gr>'lloblattidae. 



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

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

 the Hlattidac. 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 Ixpismatidac are 

 far greater than those between the IMecoptera (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, 

 NicoUtia. 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 sii^e 

 family ) . 



Very ck>sely related to the Plecoptera. on the one side, are 

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

 velo!"- •■' •< very closely paralleled by that of the Dermaptera. 

 liuU ' I forms as Arixenia (specimens of which were kind- 



Is Uwuicd me by Dr. K. Jordan), combine in themselves char- 

 .u t(>rs found in both Plecoptera and Dermaptera. and the im- 

 inuture stages of such Dermaptera as Dyscritina. Karschiella, 

 Hormansia. etc.. in which the foixeps are preceded by Plecop- 

 ttTon-like cerci. ser%c to connect the Plecoptera and Dermap- 

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

 Imes of descent. 



