NU.1438. WINGS OF THE TEXTHREDINOWEA—MacGILLIVBAY. 591 



vein toward the base of the wing there is a corresponding migration 

 of the posterior end of the stem of M.^+^ toward the apex of the wing, 

 and although this latter vein keeps relatively the same inclination, yet 

 in these genera it would end at or a little before the apex of the cell 1st 

 A. As was pointed out above, there seems to be a marked correla- 

 tion between the divergence of these veins and the widening of the 

 cell C, together with a usually well preserved Scj; an exception is 

 found in the genera Lahidarge (lig. 78) and Blasticotoma (fig. 44), 

 where the free part of Sc^ is entirely wanting and cell C is hardly more 

 than a line, but this discrepancy is due to another cause, the different 

 way in which the stress exerted in flight is transmitted from the stigma 

 to the anal margin of the wing, which is shown by the angulate condi- 

 tion of M at the origin of the stem of M3+^. If now we examine 

 another series, as X'lphydrla (tig. 85) and Xiris (fig. 89), where the 

 medio-cubital cross- vein is transverse, we find that the posterior end 

 of the stem of Mg-^^ has migrated slightly toward the base of the wing 

 and is parallel with the cross- vein. In Megalodontes (fig. 92), where 

 the cross- vein is oblique, the posterior end of the stem of M.,+^ has 

 migrated still farther, yet maintains its parallel course. While in such 

 genera as Strong ylog aster (fig. 51), Cephus (fig. 96), Phymatocera (fig. 

 71), BlennocarKpa (fig. 72), and Tenthredv (fig. 56), where this cross- 

 vein is strong!}" inclined and if continued would approximate the base 

 of the wing, there is a corresponding migration of the posterior end 

 of the stem of Mg+j toward the base of the wing which has kept pace 

 with the cross- vein, and if it were continued it would reach the margin 

 some distance before the apex of the first anal cell. 



THE CUBITAL AREA. 



The base of cubitus in most Tenthredinoidea coalesces with the 

 combined bases of radius and media for only a very short distance, for 

 one-fifth to one-sixth the length of the distance ])etween the base of 

 the wing and the apex of the cell M, The family Lydidee (figs. 36-43) 

 represent a marked sidewise development as regards this coalescence, 

 where cubitus has coalesced with R+M for fully one-third of the 

 distance between the base of the wing and the apex of the cell M. 



The free part of Cuj + M^ is almost always found extending between 

 the cells M^ and 1st A. In the Lydida? (figs. 36-43) it joins the cell 

 M^ at or beyond the middle and the cell 1st A on its apical third or 

 fourth with this end always pointed toward the apex of the wing. In 

 Matioxyela (fig. 34) it occupies a similar position except that the end 

 joining the anal vein points toward the base of the wing, while in 

 Macro.fyela (fig, 33) it joins cell M^ on its apical ^fifth and bends 

 toward the base of the wing. It is found in Paarurnti (fig. 86) near 

 the middle of the cell M^ and on the basal third of the first anal cell; 

 in Xtr'iH (fig. 89) it joins the cell Mj on its basal fourth and the 

 Proc. N. M. vol. xxix— 05 39 



