BY R. J. TILLYARD. 227 



D. Cuticularisation of the Larval Wing (PL xxxiii., figs. 2-3; 



Text-figs.5-6). 

 The wings of Diphlehia larvae well advanced in the last instar 

 show a condition not hitherto recorded in any works known to 

 me., viz., a definite cuticularisation of the larval wing, outlining^ 

 hut distinct from, the future venation of the imago. This con- 

 dition caused me considerable trouble, since I found (in the larva 

 examined at Wentworth Falls by camera-lucida drawings) what 

 appeared to be all stages in the development of a 

 ^ basal stem connecting Ms with R. At first, I 



S ^'pv: believed that it was actually trachea Ms which was 

 R__-^^53ii:: growing back on to R (how much the wish was 

 m'^H-^J father to the thought !). Dr. Bis, however, with 

 /\ ^'^ characteristic insight, at once gave it as his opinion, 

 on seeing the photographs taken from the second 

 specimen, that here was a cuticularisation of the 

 larval wing taking place, preparatory to the develop- 

 ment of the imaginal venation within. This is 

 clearly correct. We have all seen, of course, the 

 pattern of the imaginal venation left behind on the 

 larval wing-case in the exuviae, but I do not think 

 the actual formation of this pattern, as apart from 

 the formation of the true venation, has ever been 

 noted or figured. A point of interest in this cuticu- 

 larisation is that it seems to take place somewhat 

 unevenly. 



Thus in PI. xxxiii., fig. 3, we see the extreme base of Mj... still 

 unaffected, the transparent trachea plainly showing through as 

 a narrow stalk. The bases of M3 and Ms have only a little 

 cuticularisation. In the case of A', in one of the Wentworth 

 Falls specimens, the process of gradual backward growth was 

 beautifully shown (Fig. 6). Again,, in the case of Ms, as the 



* Diphlehia lestoides Selys. Last larval instar, To show progressive 

 stages in the cuticularisation of Ms and its connection with R. — A, in 

 right hindwing of first larva — B, in right forewing of first larva — C, in 

 right forewing of second larva. (Camera-lucida drawings made from the 

 under side of the wing-case). Compare PI. xxxiii., fig.2. 



