BY R. J. TILLYARD. 383 



and evolved it along a line entirely different from all other 

 Australian Zygoptera, except perhaps Argiolestes. The larva is, 

 in fact, an active predatory insect, and probably is quite able to 

 defend itself against attacks by enemies larger than itself, using 

 its labium as well to ward off attack as to capture its food, and 

 its strong legs to enable it to retreat quickly backwards into a 

 crevice if the necessity arises. I was much struck by the 

 vigorous way in which the newly hatched larvae shewed fight 

 Avhen attacked with a fine pin-point. They would back vigorously, 

 darting out their labia with great rapidity, and finally, if pressed, 

 dodge rapidly aside, all the time keeping ceaseless vigil. I have 

 never been able to provoke any other Zygopterous larva to shew 

 fight. In this respect, Diphlebia resembles some of the large 

 jEsclmidce, whose larvae, dwelling on submerged sticks and twigs, 

 stalk their prey with great perseverance and watchfulness. 

 Possibly this may suggest the reason for the convergence in the 

 iorm of its labium to that of an ^schnid. 



In conclusion, I regret that my attempt to raise this interesting 

 larva has been only partially successful. Probably a closer 

 approximation to natural conditions — running water, and 

 animalcula obtained from its natural haunts — may be the road to 

 final success. 



EXPLANATION OF PLATE XXXIII. 



Diphlebia lesto'ides. 



Fig.l. — Exuviae ( x4). N.B. The caudal gills, enclosed in a dotted square, 

 are supplied from a sketch of those of a larva four months old; 

 those of the exuviae are shrivelled. 



Fig. 2. —Labium. 



Fig.3, —Ova, a, one week old; 6, five weeks old, 



Fig. 4. — Larva one week old. 



Fig.o.— Antennse of four-months-old larva. 



