NO. 1438. WINGS OF THE TENTHREVINOIDEA—MacGILLIVRAY. 579 



niarj^-in of the wing- (tigs. 6-7). This coalescence continues until the 

 free parts of Ckij and Cu.^ appear like short cross-veins near the middle 

 of the wing-. At the same time that the apices of the branches of 

 cubitus are combining with the anal veins, the base of cubitus migrates 

 toward the front margin of the wing, combines with the united base 

 of radius and media (tigs. 0-8), and closes the base of the cell ]M. 

 With the migration forward of the base of cubitus, the combined 

 bases of 1st A and 2d A, also mig-rate forward to till the space vacated 

 by the base of cubitus. 



The media, M, lies just in front of and parallel with the cubitus (fig. 

 1). Near the middle of the wing it divides into two branches, each of 

 which divides again. With the migration and coalescence of the tips 

 of cubitus and anal veins there beghis also a migration of the three 

 posterior branches of the media (tigs. 2-5). M^ eventually combines 

 with the combined tip of the anal veins and cubitus, closing the cell 

 M^ at the margin of the wing (tig. 6), migrates along this vein, and 



'M^R.., 



1st A+2d A+3d ^Ciifu, 



Fig. 4.— Modified hypothetical wing. 



combines with the tip of the free part of Cuj, crowding the cell M^ 

 back still farther from the wing margin (tigs. 7-8). Mg, pulled along 

 by the same force that combined M^ with the anal veins and cubitus, 

 migrates along the margin of the wing* and combines with the tip of 

 the spur-like vein situated at the apex of the first anal cell. In this 

 way the cell M^ is closed at the margin of the wing. The spur-like 

 tip now consists of the combined anal, cubitus, and two posterior 

 branches of media. The tip of the vein 1st A+2d A+3d A+Cui^2+ 

 M3+4 has been lost, so as to permit of the folding of the posterior 

 margin of the wing where the hooks of the hind wing are fastened. 

 Mg, tied to M3 by the medial cross-vein, is also pulled around the wing 

 margin, changing from a longitudinal to a transverse position, while 

 the medial cross-vein is transformed from a vein extending trans- 

 versely to one extending longitudinally (tigs. 5-7). The first branch 

 of media maintains its primitive position near the middle of the wing 

 throughout the entire series. The stem of media very early migrates 

 forward and combines with the stem of radius (tigs. -1-7), thus com- 



