140 



THE WINGS OF THE ISOPTERA 



The wings of different adult individuals of this species differ greatly in 

 the number and arrangement of the veins of the subcosto-radial area of the 

 wing. In the fore wing represented in Figure 131, there are only three 

 distinct veins in front of vein R4+5. This condition corresponds with the 

 tracheation of the wing of a nymph represented by Figure 130; and conse- 

 quently these veins are designated as veins Sco, Ri, and R2+3 respec- 

 tively. 



In some individuals, however, there is no reduction in the number of the 

 veins in this part of the wing. Figure 132 represents the base of a fore 

 wing of this species in which all of the veins of the subcosto-radial area are 

 preserved. 



Holmgren ('11) figures the base of a fore wing of this species in which 

 there are only four veins crossing the htmieral suture in front of media. 



This condition corres- 

 — C 



/?4+5 



the trach- 

 wing of a 



ponds with 

 cation of a 



nymph represented in 

 Figure 130 ; and I believe 

 that the veins in the indi- 

 vidual figured by Holm- 

 gren should be identified 

 as are the tracheee in 

 Figure 130. H olmgren 

 recognizes a subcosta, a 

 double "radius" (1.^. Ri), 

 and a radial sector, which 

 is my R4+5. The differ- 

 ences between our inter- 

 pretations of the homo- 

 logies of these veins is 

 doubtless due to his con- 

 clusion that in Mastotermes vein Ri is represented by two distinct parallel 

 veins, a conclusion that is based on what I regard as an instance of aberrant 

 tracheation as stated above. 



The hind wing of the Termopsis angiisticollis figured here (Fig. 131) 

 differs from the fore wing in that there are only two distinct veins between 

 vein Rif.^ and the thickened costal margin. 



An examination of the tracheation of many hind wings of this species 

 convinces mc that these two veins are vein Sc2 and vein Rs+s- The sub- 

 costal trachea is unmistakable, as it enters the wing distinct from the radial 

 trachea; trachea Sci is usually merely a short branch, while trachea Sc2 is 

 well developed. In a few specimens there is a small vestige of trachea Ri, 

 but in all trachea R2+.3 is well developed. 



Fig. 132. 



-Base of a'fore wing of Termopsis 

 angtisticollis. 



