Vol. XXJi] 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, M/}., A 

 and Cu2; distal half, C, Ri, Mia, two supplementary sectors, 

 Rs, three supplementary sectors, M/|., Cu2a, Cu2b. 



Concave veins: proximal half of wing, Sc, Mi, M3, Cui ; 

 distal half. Mi, two supplementary sectors, M2, one supple- 

 mentary sector, M3, two supplementary sectors, Cui, 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), Ri (first branch of radius), Mi (first branch of 

 media), A (anal), Cu2b and the supplementary sector between 

 Cu2a and Ci\2b. 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 



