BY R. J. TILLYARD. 751 



of the wings of the pupa, in order to study the tracheation. 

 Including a considerable number of bred specimens of this species, 

 I have had through my hands for study, at one time or another, 

 about one hundred examples of these rare insects, and have thus 

 been enabled to gain a first-hand knowledge of all the Australian 

 species except one. That exception is Psi/chopsis meyricki 

 McLachlan, of which the only known specimens are in the 

 McLachlan Collection, and are, therefore, not available for study. 



In the present paper, I propose to deal fully with the wing- 

 venation of the family, firstly by a study of the pupal wing- 

 tracheation, and secondly by applying the results so obtained to 

 elucidating the best method of founding genera in the family. 

 This matter is one of considerable difficulty, owing to the essen- 

 tial variability of the characters selected for this purpose by 

 Navas, viz., the amount of cross- venation present. Descriptions 

 of new genera and species will also be included, together with a 

 general discussion of the relationships of the family. The full 

 account of the life-history of Psychopsis eleyans (Guerin) will 

 form a separate paper, No. 7 of this series of Studies. 



My thanks are due to Dr. R. Hamlyn Harris, Mr. H. Long- 

 man, and Mr. H. Hacker, for the three fine photomicrographs 

 reproduced in Plate Ixxvi. 



The Venation of Psy chop sis eleyans (Guerin). 



In Text-fig. 1, the complete venation of Psychojjsis eleyans 

 (Guerin), is shown. Text-figs. 2, 3 A, give, for comparison, portions 

 of the precedent tracheation of the pupal wing, drawn by means 

 of the camera lucida from freshly dissected pupal wings. 



It will be seen at once that, broadly speaking, the venation 

 and the precedent tracheation agree remarkably closely, as is the 

 case with all the more archaic members of the Order Planipennia. 

 Tracheae precede every main vein, right down to its tiniest 

 branchlets; but no tracheae precede the cross-veins, which are 

 only lightly indicated on the pupal wing. It is, therefore, very 

 necessary that we should be careful to distinguish between the 

 true cross-veins in the imaginal wintj, and those veinlets (or 



