ENTOMOLOGICAL NEWS [Jan., '22 



latter vein is called by Needham and others Rs. 1 While 

 accepting, in the past, this terminology, as far as the Anisoptera 

 are concerned, I have pointed out that, in the Suborder Zygop- 

 tera, the trachea supplying this vein is a branch of M, and 

 never has any connection with R at all. Hence I have claimed 

 that the corresponding vein in the Zygoptera cannot rightly be 

 called Rs, and I have suggested the name "Zygopterid Sector" 

 for it, with the notation Ms. z 



The full account of Needham's Theory of the crossing of 

 Rs over two branches of M, viz. Ml and M2, is by now so 

 well known to all Odonatologists that I shall save space by not 

 recapitulating it here, and shall only refer my readers to Need- 

 ham's very clear account of it (1). The chief point of im- 

 portance to be noted is the claim that the oblique vein, of which 

 there is only one present in most Anisoptera, represents the 

 original position of crossing of Rs below M2, while all that 

 part of the main vein lying below it basad from the oblique 

 vein is a new formation, not represented in the original Odonate 

 type, and designed to strengthen the wing for flight. This part 

 is called by Needham the bridge-vein. In the larval wing the 

 bridge-vein is formed by a pigment-band only, without any 

 precedent tracheation, and it is this fact, more than any other, 

 which has influenced Needham in forming his conclusions. 



No satisfactory explanation has ever been offered of the 

 condition of things in the Petaluridac. where two oblique veins 

 are always present. For many years I have endeavored to find 

 suitable stages of the larvae of Petalura. from which to solve 

 this problem ; but the search has been unsuccessful, owing to 

 the draining and cutting up of the swamps on the Blue Moun- 

 tains in which I originally found this larva. 



In November, 1919, I visited New Zealand, where I stayed 

 five months. While at Wellington at the beginning of De- 



1 Needham, J. G. "A genealogic study of Dragonfly Wing Venation." 

 Proc. U. S. Nat. Mus., Washington, No. 1331, 1903, xxvi, pp. 703-761, 

 24 pi. (See especially Figs. 1-2, pp. 706-7, and 710-714.) 



2 Tillyard, R. J. "On the Development of the Wing- Venation in 

 Zygopterous Dragonflies, with special reference to the Cahfterycfidae." 

 Proc. Linn. Soc. N. S. W., 1915, xl, pt. 2, pp. 212-230. (See p. 224 and 

 plates.) 



