228 STUDIES IN AUSTRALIAN KEUROPTERA, iii., 



old, and was treated as explained for the pupa of Chrysopa B 

 above. The dissection was carried out with the greatest care. 

 But though tliere was scarcely any displacement of the trachea- 

 tion, it was found that a certain amount of blood-plasma, and 

 some fatty tissue, had found their way into the bases of the wings, 

 rendering them too opaque for observation. 



Further pupte were now taken, all about one day old, since it 

 appeared that only on the first day or two were the wings free 

 fi-om rucking within the wing-sheath. The wings were carefully 

 dissected off, but in no case could T obtain a satisfactory result. 

 The wing-sheaths were so delicate that the use of a cover-slip 

 completely upset the tracheation; also it seemed quite hopeless 

 to use the scissors without causing some alteration in the positions 

 of the main tracheal stems. 



I now tried the following plan, which 1 am glad to say proved 

 entirely successful, and enabled me to obtain the results shown 

 in this paper. Having determined that the tracheation must be 

 studied without the use of any dissecting methods, I took a pupa 

 of (J. sufnata about one day old, and killed it in the usual manner. 

 I then took two glass slides, and moistened them so as to make 

 them cling firmly together. The upper slide was selected so as 

 to be as near as possible of a thickness e<(ual to the height of the 

 [)iipal thorax up to the wing-base. This slide was then slipped 

 back along the lower one, so as to leave nearly an inch of the 

 latter exposed. T then took hold of the pupa by the legs with a 

 fine forceps, cut off and removed the right anteinia, and carefully 

 .Separated the two wings on the right side, with the point of a 

 fine needle. (The mark made by the needle can be seen as an 

 obli([ue depression ruiuiing in from near the middle of the pos- 

 terior border of the hinflwing in Plate xi., fig. 1). The i)Upa was 

 tlien i)laced carefully down, dorsum upwards, on the free portion 

 of tlic lowei- slide, the right pair of wings being raised up so as 

 to })roject at right angles to the body-axis, supported upon the 

 upper slide. The pupa and its wings were kept thoroughly wet 

 with water during this operation. Finally, the body of the pupa 

 was gently pressed until it came to lie close up to and parallel 



