BY R. j. TILLYARb. 



753 



braiichlets of main veins) which arc preceded by trache.T. For 

 example, the veinlets passing from 8c to the anterior border are 

 true veinlets or branches of Sc; but, in families where they are 

 not so prominently developed as in the l\sijchoj)sid(e, they are 

 frequently spoken of as cross-veins. The small veins which join 

 these veinlets together, forming a longitudinal series of gradate 



Text-fig.2. 

 P-sf/rhopsIs eJegans (Giierin). Tracheation of basal half of pupal wing; 



( X 18). Lettering as in Text-fig. 1. 

 veins, are true cross-veins, and are to be regarded as a com- 

 paratively late acquisition, correlated with the broadening out 

 of the costal area in this family. So, also, the three other series 

 of gradate veins are true cross-veins, not being preceded by 

 tracheie. A further point of distinction between veinlets and 

 cross- veins, in this and all other archaic families of Planipennia, 

 is that the veinlets, like the main veins of which they are part, 

 are hairy, whereas the cross-veins are not. 



