Vol. xxii] ENTOMOLOGICAL NEWS 59 
haps the two surfaces of the wing rudiment might present only 
convex and concave veins respectively. Turning then to the 
imaginal wing the following lists were made proceeding in 
every case from the anterior toward the posterior wing margin. 
Convex veins: proximal half of the wing, C, Ri, Rs, M4, A 
and Cuz; distal half, C, R1, Mia, two supplementary sectors, 
Rs, three supplementary sectors, M4, Cuza, Cu2b. 
Concave veins: proximal half of wing, Sc, M1, M3, Cur; 
distal half, M1, two supplementary sectors, M2, one supple- 
mentary sector, M3, two supplementary sectors, Cul, one sup- 
plementary sector between Cu2a and Cu2b. 
As is well known the inner surface of the wing-pad and 
wing-rudiment of an Odonate larva corresponds to the upper 
surface of the imaginal wing, and the outer surface in the 
larva to the under surface in the imago. On comparing the 
list of convex veins with the drawing of the inner surface of 
the wing-rudiment and the list of concave veins with that of 
the outer surface of the wing-rudiment, it was seen that a 
close correspondence existed with these exceptions: that C 
(costa) showed on both surfaces, as also did a thickening all 
along the posterior margin and to greater or less extents Sc 
(sub-costa), Rr (first branch of radius), Mt (first branch of 
media), A (anal), Cu2b and the supplementary sector between 
Cuza and Cu2b. The wing-rudiment was then cleared in cedar 
oil and examined in strong transmitted sunlight, when the 
vein-rudiments of both inner and outer surfaces could be seen 
from either surface by proper focussing, whereas before clear- 
ing only those of the surface turned up toward the lens could 
be discerned. All the vein-rudiments now appeared in their 
proper sequence giving the alternation of convex and concave 
veins so easily seen in an imaginal wing. Careful focussing 
also revealed the fact that at this stage the veins are developed 
only upon one surface of the wing-rudiment, either inner or 
outer, except in the case of the costa and of the thickening 
along the hind margin. The other exceptions noted above are 
all veins near the margins where the wing-rudiment is thinner 
