THE WINGS OF NEUROPTERA 



157 



accessory \'eins? In other words, to which end of the series of branches of 

 the radial sector are the accessory veins added? 



Comstock and Needham concluded from their studies of the tracheation 

 of the wings of pupae of Chaiiliodes (Fig. 140) and Corydalus (Fig. 151) that 

 in the case of these insects the accessor}^ veins are added to the distal end 

 of the series. The presence of fine twigs at the tip of trachea Ro indicated 

 to us the method of increase, which we concluded to be as follows: 



The fine tracheal twigs at the tip of trachea R2 are the beginnings of 

 accessory branches, which in the course of phylogenetic development 

 become larger and, moving towards the base of the wing, make room for the 

 addition of other branches. 



From this it follows that vein R2 forms the tenninal portion of the stem 

 of the pectinate vein and that veins R5, R4, and R3 are the proximal branches. 

 It also follows that of the accessory veins that have been developed on vein 

 R2 the proximal one is the oldest, and according to our system should be 

 labeled R^a, as is done in Figures 140 and 151. 



My studies of the venation of the wings of insects during the twenty 

 years that have elapsed since these conclusions were reached have only 

 served to confirm them ; and I am now convinced that what we showed 

 to be the case in Chauliodes and Corydalus is true primarily of all of 

 those neuropterous insects in which the radial sector is pectinately 

 branched. In some cases, however, to be discussed later, accessory veins 

 are interpolated in the primary series by the splitting of members of this 

 series. 



I am led to make this statement because some of the writers on the 

 Neuroptera have not accepted these conclusions. Thus Enderlein ('10) in 

 his figures of the wings of Mantispids numbers the branches of the radial 



3<i A 2d A 



Cm C«x« 



Fig. 151. — Tracheation of a wing of a pupa of Corydalus cornulus 

 (after C. & .\.). 



sector from the apex of the wing towards the base; and Till yard ('16, p. 

 277) violently attacks the view of Comstock and Needham. For this 

 reason it seems incumbent upon me to give the additional data that have 

 confirmed my belief in this view. 



