376 STUDIES IN THE LIFE-HISTORIES OF AUSTRALIAN ODONATA, 



Towards the end of March, I carefully examined the larv^a and 

 made a sketch of it. Length over all 8-5 mm., of which the 

 caudal gills account for about 3 mm,; colour pale straw. Head 

 rather square in front, with labium projecting slightly beyond it 

 like a flat shelf. Antennce, seven-jointed, with the second joint 

 elongated, the others shorter and about equal in length, except 

 the top joint which is very thin and short; basal joint thickened; 

 bases of joints 3-6 white, rest dark; second joint with small hairs 

 all along it; a small tuft of two or three hairs at distal end of 

 joints 3-6 (see Plate xxxiii., fig. 5). Eyes black, with stiff hairs 

 just below them. Prothorax and forelegs very strong and well 

 developed, smooth. Meso- and metathorax together not much 

 larger than prothorax; middle and hind legs fairly long, smooth. 

 Abdomen rather short, thick, segments all very short; segment 10 

 fairly wide. Caudal gills 3 mm.; the lateral ones thick at bases, 

 strongly triquetral, the cross-section apparently a triangle with 

 base nearly flat and slant sides convex rather than concave; 

 median gill less triquetral, narrower at base, projecting in a 

 vertical plane at an angle of nearly 60° above the other two, 

 which diverge in a horizontal plane at about the same angle. 

 Under a lens the two main tracheae can be seen branching out 

 from the base of each gill, but these become transparent and soon 

 divide up into innumerable smaller tracheae which are practically 

 invisible. For the first half of their length the gills increase in 

 width, the top edge being convex, especially in the median gill; 

 they then narrow rapidly to a long thin point, the last two-fifths 

 being very hairy. 



Towards the middle of April the nymph forsook its perch on 

 the twig and hid under a shell, preparatory to another ecdysis. 

 Soon afterwards it returned to the twig for a short time, and 

 appeared very restless. I judged from its dark colour that the 

 ecdysis was not yet over. During the next few days it became 

 very sluggish, but fortunately it took up a position between a 

 white shell and the glass of the jar, where I could watch it easily. 

 On April 3rd, I noticed several water-fleas clustering round it, 

 and on examination I found that it was dead, having only 



