4 MR. R. J. TILLYARD : LIFE-HISTOEIES AISTD 



exactly as M bends away from R at the arculus. This portion o{ A 1 have 

 designed the "anal crossing" [Ac). It is at this point that the future 

 " first cubito-anal " cross-vein is laid down, and its persistency in all forms 

 is a necessity, since it is a part of the true anal trunk. 



At the posterior end of Ac, A branches into two (sometimes three). One 

 branch, A^, runs back basad parallel to Cu+ A above it, but not very far. 

 Along the course of this trachea the vein called " anal " by Needham is laid 

 down as a kind of bridge-vein connecting to the posterior border of the true 

 wino-base, and forming the attachment for a special rotator muscle. This 

 vein is, strictly speaking, not A at all, but the secondary anal vein, A'. 



We thus see that Needham's Cu is really Cu + A as far as Ac, while his 

 A is really A'. 



From Ai, very close to its origin from Ac, a strong trachea A3 descends 

 towards the wing-border (in some forms A^ descends directly from Ac). 



The second branch of A from Ac runs distad, giving ofl": a branch A 2 not 

 far from Ac, and then running on, as Ai, to meet Cu2 near its point of 

 bifurcation from Cui. It then joins Cug for a short distance, and finally 

 breaks away from it again and curves inwards basad. Hence the anal loop 

 of the ^^schiince is enclosed between A^, and A^ entirely. Needham has 

 correctly determined these parts for the yEsclmina;, but not for the other 

 subfamilies. 



In fig. 3 I give the amended nomenclature on a diagram of the wings of 

 ^sclvna hrevistyla. The necessity of the alteration will be at once seen by 

 comparison of the adult venation with the nymphal tracheation. 



As regards the life-histories many gaps still remain, and the field for 

 observation of small but interesting and often very important points is 

 almost unlimited, and open to any earnest field-worker to follow up. These 

 large Dragonflies are the most difficult of all to study, owing to the great 

 rarity of most species, their rapidity of flight, and their shyness. The 

 student of the y^Hsclininoi must have an unlimited supply of patience, and 

 must be content to add, year by year, only a fact here and a fact there, until 

 he approximates to a full knowledge of each ])articular case. I have fortu- 

 nately been able to discover larv?e representative of every genus in Australia, 

 with the single exception of Austrogy7-tacantlia ; but only in very few cases 

 can I give at all a complete account of the life-history. 



During the course of my studies on this group, I have been particularly 

 struck with the close agreement between the accepted phylogeny of the 

 ^schnince and their present geographical distribution (in the case of the 

 Australian forms). I have, therefore, adopted the somewhat novel, but I 

 hope fully justified, expedient of subdividing them into geographical groups 

 based on their present distribution in relationship to the continent of 

 Australia. This subdivision will be found to correspond exactly with the 

 accepted phylogenetic classification. For convenience of reference, I have 



