172 
Psyche 
[December 
served the most primitive venation of any living members 
of the superorder, while the Isoptera have preserved the 
various features of the body in as primitive a condition as 
any members of the superorder. These insects are the 
most primitive of the Orthopteroid insects, and are prac- 
tically the direct descendents of the Protoblattid type of 
Protorthoptera. 
The Embiids and Plecoptera are included in a superorder 
called the Panplecoptera (or Plecopteria) , characterized by 
the fact that the postscutellum of the mesothorax is well 
developed, and the trochantin of the mesothorax unites 
basally with the episternum above it, in the members of this 
superorder. The mesothoracic coxae tend to become ring- 
like rather than conical, and the tarsi are trimerous. The 
eighth and ninth abdominal segments are not greatly nar- 
rowed in the females of these insects, which are ovipositor- 
less. The Plecoptera are usually grouped with the Odonata 
and Ephemerida (rather than with the Embiids among the 
Orthopteroid insects) but the character of their thoracic 
sclerites is so strikingly similar, and the venation of the 
fossil forms intergrades so markedly, that there can be no 
doubt that the Embiids and Plecoptera are extremely closely 
related, and were descended from a common Protorthopteran 
ancestry. The fossil Protoperlaria are rather specialized 
Plecopteroid insects which branched off at the base of the 
Plecopteran stem, and the fossil Protembiids apparently 
branched off at the base of the Embiid stem, but the actual 
Protorthopteran ancestors from which all of these insects 
were ultimately derived have not as yet been discovered. 
The Orthoptera (including the Grylloblattidse) and the 
Cheleutoptera, or Phasmida, and possibly the Dermaptera 
also (although the closest affinities of the Dermaptera may 
be with the Blattoid insects comprising the superorder 
Panisoptera) , are included in the superorder Panorthoptera 
(or Orthopteria) , characterized by the huge development of 
the anal fan, and the consequent reduction of the preanal 
region of the hind wings. The ovipositor is well developed 
in most of them, and is overlapped basally by the eighth 
abdominal sternite (excepting the Dermaptera, which may 
not belong in this superorder). The male genitalia are 
usually rather symmetrically developed and the cerci fre- 
