1930 ] Wing Venation of the Odonata and Agnatha 247 
3, the curve of the cubitus (chiefly in the Anisoptera) and 
beyond this curve, the formation of the two branches, Cui 
and Cu 2 ; formation of a triangle (or quadrilateral. 4, small 
size of the anal vein and its fusion with the cubitus. 
It is necessary to add that according to the authors’ 
understanding the continuation of RS to M 1+2 is clearly 
a secondary vein (“bridge”) and appears to be the basal 
part of the analogous vein indicated by Tillyard (14). 
The venation of the Agnatha, as usually interpreted 
(Eaton, Comstock 1899, Handlirsch, Ulmer and others), 
is entirely different from that of the Odonata, and much 
more similar to that found in the more primitive Palaeo- 
dictyoptera (Dictyoneuridae) . The media is simple and 
forks only in the distal part; RS is large and forms 4-5 
branches ; Cu is divided at the base, and the down curve is 
formed only by the lower branch; the anal veins are well 
developed. These differences in the interpretation of the 
wings of the Odonata and Agnatha are so great that the 
dragon-flies would on this basis be moved far off from the 
may-flies ; but this contradicts the sum of all data in 
morphology and the development of these insects. If vena- 
tion means anything in the explanation of phylogenetic 
relations of the different groups — as is unquestionably so, 
and the venation of the dragon-flies has been studied par- 
ticularly carefully from this point of view — then either 
the evidence of morphology and history of development, 
which indicate a close relationship of the Odonata and 
Agnatha, are wrong; or the interpretation of the wing 
venation of Odonata or perhaps the Agnatha is incorrect. 
As the close relation between the Odonata and Agnatha 
is not disputed, the author began to doubt the accuracy 
of the usual interpretation of venation of the may-flies 
and partly of the dragon-flies. 
It is well-known that Comstock and Needham based their 
interpretation of the wing venation in different groups on 
the study of the tracheation of the wings of nymphs and 
pupae. This tracheation, it is supposed, reflects the more 
primitive condition of venation. The trachea RS of the Odo- 
nata (Anisoptera) turns off from R and, after crossing the 
bases of tracheae 1VC and M 2 , enters the region between 
