Vol, xxvii] ENTOMOLOGICAL NEWS. 305 
the basis of the closeness of their lines of descent. These are 
as follows: 1. The section Palaeopteradelphia, or Palaeop- 
teron (Blattid) brotherhood, comprising the Blattids (and 
possibly the Mantids also.) 2. The section Plecoptera- 
delphia, or Plecopteron brotherhood, comprising the Ple- 
coptera and those insects whose lines of descent parallel 
that of the Plecoptera (e. g., the Embiids, Forficulids, Gryllo- 
blattids, Coleoptera, Termites, Gryllids, Tettigonids, Locustids, 
Phasmids, Phylliids, etc.). 3. The section Neuropteradelphia, 
or Neuropteron brotherhood, comprising all of those forms 
descended from ancestors similar to those of the Neuroptera 
(e. g., the Neuropteroid insects, Homopteroid forms, Hemip- 
tera, Lepidoptera, Diptera, etc.). 4. The Zygopteradelphia, 
or Zygopteron brotherhood, comprising a small aberrant group 
(Anisoptera, Zygoptera, etc.), which may possibly be included 
in one of the other sections. 5. The Plectopteradelphia, or 
Plectopteron brotherhood, comprising the very primitive though 
strongly aberrant Ephemerid group. These five sections rep- 
resent five evolutionary groups, although some of them might 
possibly be included in certain of the other groups, thus re- 
ducing the number; but I think that each of the five is distinct 
enough to merit being regarded as a separate line of evolution. 
The section Plecopteradelphia (Plecopteron brotherhood) 
and the section Neuropteradelphia ( Neuropteron brotherhood ) 
comprise the greater part of all winged insects, and are thus 
by far the most important of the evolutionary lines. Whether 
the Plectopteradelphia (Ephemerid brotherhood) and Zygop- 
teradelphia are sufficiently distinct from each other and from 
the Plecopteron group, to be considered as separate sections 
is open to question; and the fact that the Palaeopteradelphia 
(Blattid brotherhood) is closely related to the Plecopteron 
group also raises the question of its being sufficiently distinct 
to be regarded as a separate section. It must be borne in 
mind, however, that all of the sections are ultimately closely 
related, and the Plecopteron group itself is closely related to 
the Neuropteron group, but both appear to represent definite 
foci about which numerous other forms cluster ; and the other 
