144 Dr. G. C. Orainptoii on the Prinntive 



Mastotermes, the sternite of the seventh, or jjreceding 

 segments, as well as the eighth sternite, may form the plate 

 below the genital apparatus of female insects in general. 



In comparing together the terminal structures of insects 

 in general, I have been impressed with the marked resem- 

 blance between the terminal structures of the sawfiies 

 and those of the termites (with the exception of the genital 

 apparatus of the males, since the styli of male termites 

 apparently become modified to form clasping organs in 

 the male sawfiies), and there are a number of features which 

 point to a rather close relationship between the two groups. 

 These resemblances have led me to conclude that the Pso- 

 cidae {s. I.), Hymenoptera, Mecoptera, Neuroptera, and 

 Coleoptera probably arose from ancestors anatomically 

 intermediate between the Isoptera (with the Zoraptera) 

 on the one hand, and the Dermapteron-Embiid-Plecopteron 

 group on the other. Furthermore, the Isoptera are them- 

 selves intermediate between the Blattodea (with the Manto- 

 dea) and the Dermapteron-Embiid-Plecopteron group, 

 and because of this phylogenetically important position 

 which they occupy with relation to the lines of descent of 

 the other orders of insects, their anatomy shoidd be more 

 carefully studied than has been the case heretofore. 



I have suggested in previous papers, that the Palaeo- 

 dictyoptera, Ephemerida and Odonata might possibly be 

 associated together in a section of the Pterygotan insects, 

 and while this arrangement holds good for certain of the 

 Palaeodictyoptera, it is not true of all the insects included 

 in this order, which appears to be a very heterogeneous 

 conglomeration of insects, of which certain forms are not 

 sufficiently nearly related to be included in the same order, 

 or even superorder. Thus for example, I would now con- 

 sider such Palaeodictyoptera as the Stenodictyoids (or 

 those related to Stenodiclya) as belonging in the superorder 

 Panplecoptera, which includes the Plecoptera, Embiodea, 

 Dermaptera, Cijlcoptera and their allies (to which might be 

 added such fossil fcu'ms as the Hadentomodea, Haplop- 

 terodca, etc., although I am not certain as to such forms as 

 the Sypharopterodea). On the other hand, some of the 

 insects now placed in the order Palaeodictyoptera, such 

 as the Eubleptidae, bear a strong resemblance to the insects 

 comprising the superorder Panplectoptera, composed of 

 the Ephemerida (also called Plectoptera), Protephemerida 

 {Tri'plosoha) and their aUies. Handlirsch would derive 



