60 ENTOMOLOGICAL NEWS [Feb., 711 
and where they can be seen through it. Even in these ex- 
ceptions the veins appear fainter and narrower on one sur- 
face than the other and are stronger and wider on their proper 
surface, e. g. Sc and Mt, concave veins, on the outer surface; 
R1, A and Cu2b, convex veins, on the inner surface. 
Another fact shown by these comparisons and the figures 
is that the cross-veins only appear continuous from one longi- 
tudinal vein to another when the two longitudinal veins so 
connected are two, one of which immediately follows the other 
in the imaginal wing. (Cf. the cross-veins between R1 and 
Mi and between M1 and M2 in PI. III, fig. 24.) 
It would thus appear that each longitudinal vein develops on 
one surface of the wing-rudiment before it appears on the 
other surface. Before transformation is reached each vein 
has formed on both surfaces of the future wing but not neces- 
sarily equally on both surfaces, as may be seen from Hagen’s 
figures (1889) from photographs of wings split into their two 
laminae immediately after transformation and expansion. 
These facts of the development of the veins on one surface 
of the wing-rudiment before the other have a practical value 
in identifying Odonate larvae by this method and do not seem 
to be included in Prof. Needham’s (1904, p. 687) suggestions 
on this point. 
In the larva of Cora there exist the following generalized 
features: antennae with no hypertrophied joint, biramous man- 
dibles, paired ventral tracheal gills (if they be morphologically 
equivalent to legs), and perhaps the empodium-like part, side 
by side with specialized features in the form of cuticular 
scales, almost completely fused halves of the labium and thick- 
ened, shortened caudal gills. If to these generalized parts of 
the larva we add the generalized features of the imaginal 
venation pointed out or implied by Prof. Needham (1903@, 
pp. 731, 746), we have good grounds for looking on Cora and 
its allies as being in many respects the most primitive of living 
Odonata. 
