1923] 
The Wing-V eolation of Insects 
131 
only the ultimate; it corresponds to lA in the Odonata, and, 
just as with the latter, it is attached along a certain length to 
the nervure which precedes it, supporting the secondary ner- 
vures which are opposite in direction to those which are sup- 
ported by the sector of the penultimate. The Protodonata also 
seem to have three anal nervures, P, and S'p and U, U rejoining 
the common trunk of P and Sp after this has left Scu. 
In the Odonata, on account of the attenuation of the base of 
the wing, the attachment of the sub-cubital and penultimate 
extends farther than in the Protodonata, the sub-penultimate is 
missing, and the ultimate is attached in part to the portion 
common to, Scu and P. 
The essential differentiation between the Protodonata and 
Dictyoptilus lies in the reunion of the median to the base of the 
radial and the disappearance of the anterior cubital; the Odonata 
are derived from the Protodonata by the suppression of the 
posterior median and of the sector of the penultimate nervure. 
It remains for us only to inspect the neuration of the Rhyn- 
chota. Is what we call the median in Endoblastic insects the 
nervure Sm of the Subulicornia or rather the nervure M of the 
Ectoblastic insects? The study of existing forms does not permit 
us to decide. Let us then have recourse to paljeontology. 
The numerous Protohemiptera of the coal measures^^ offer a 
complete wing-neuration ; but in all the anterior median is 
simple, and the anterior cubital is ordinarily so. 
The real Hemiptera, Rhynchota which undoubtedly des- 
cend from the Protohemiptera and ot which a representative is 
known in the Stephanian, have a forked median and cubital, 
and the two branches of these are ramified. It is sufficient to 
consider the neuration of the permian genera Scytinoptera and 
Prosbole, in Handlirsch’s Atlas to be presuaded that with 
neither the Homoptera nor the Heteroptera is there an anterior 
median or an anterior cubital, that the position of these nervures 
is occupied by a great empty space and that the two forked 
nervures are the sector of the median and the sector of the 
cubital. 
The evolution of neuration in the Hemiptera thus takes 
