SS2 kADlAL AND ZyGOPTEKID SECTOHS, &C., 



must have captured trachea Ms j)er saltnm just in the same way 

 tliat trachea Ms has captured trachea M3 in the Neonticta 

 aberration, leavivy thp original basal purtion of vein Ms existinc/ 

 as the long bridge, while the new base of Ms became the oblique 

 vein. 



The fact that, in Synlestes, the oblique vein cannot always be 

 determined, is evidence in favour of this view. If a large 

 number of larvpe were to be examined, may not some of them 

 still possess the original tracheation in one or more wings? The 

 imaginal venation from such a wing would lack the oblique vein. 



It becomes neces.sary, also, on this new view, to examine the 

 earliest wing-buds of the Lestidic, with a view to determining the 

 original position of trachea Ms with respect to M, as shown by 

 the ontogenetic evidence. Such an examination I hope to carry 

 out later on. 



Text-fig.o. — Formation of the two oblique veins (Oj , Oo) in Cordnlegaster. 

 Ms?, the trachea wliicli, it is suggested, was originally Ms, and has 

 been captured per ■•<a//iti)i by Rs. Adapted from Needham. 



(6) The b)-idgf of Anisoplera. In this case, any cpiestion of 

 Rs having become hitched to Mo per salttim cannot be enter- 

 tained, owing to the fact that the ontogenetic evidence is abso- 

 lutely against it. We must either accept Needham's view of 

 this bridge as correct —i.e., it is secondarily formed to strengthen 

 the unilateral fork or we must seek for some other explanation. 



It is well known that, in the subfamilies Cordulegastrinc^ and 

 Pet'ihirince (the two most archaic subfamilies of the Anisoptera), 

 there are two oblique veins present (Text-tig. 5, Oj, Oo). This is 



