THE WINGS OF I SOFTER A 



139 



that of Mastotermes in the arrangement of its principal branches, except 

 that trachea R2+3 is not divided. Trachea Ri separates from trachea R at 

 the base of the wing; the first forking of the radial sector trachea takes 

 place very close to the point where it separates from trachea Ri, as is the 

 case in Mastotermes, and the anterior branch of this trachea, trachea R2+3 

 is much weaker than the posterior branch ; it is not divided, and extends a 

 little more than half the length of the wing. I have been unable to deter- 

 mine whether trachea R2 and R3 coalesce or whether one of them has 

 atrophied. In either case the single trachea that remains represents the 

 anterior division of the radial sector trachea and may be designated as 

 trachea R2+3 provisionally. The posterior branch of the radial sector 

 trachea, trachea R4+5, is the largest trachea in the wing; it gives off seven 

 parallel branches from its anterior side and several irregular branches from 

 its posterior side. The medial trachea is large ; it gives off several irregular 

 branches from its anterior side and five prominent parallel branches from 

 its posterior side. The cubital trachea is six branched. 



It is evident that in Termopsis, as in Mastotermes, the most important 

 part of the radius is vein R4+5; it is the branches of this vein that support 

 the larger part of the radial area of the wing. All of the tracheae in front of 

 trachea R4+5 are comparatively weak, suggesting the approaching'^loss of 



Fig. 131. — Wings of Termopsis angusticollis. 



the veins that they represent, and it is probable that where the radius is 

 represented by a single vein, as is the case in the more specialized genera, 

 this vein is vein R4+5. 



