378 STUDIES IN THE LIFE-HISTORIES OF AUSTRALIAN ODONATA, 



Total length (excluding gills) 23-5 mm. Head large, 55 mm. 

 wide, rather flat, slightly convex above; eyes not prominent, but 

 well inset, the postocular lobes large, smooth, rounded; just 

 under the eyes, in front, is a series of sharp curved spines, four 

 in number, of which the front one is thick and strong; there is 

 also a set of smaller spines near base of antennte. Aiitennce very 

 long, 7mm., smooth, thin, filiform, second joint very long. (Notice 

 that the hairs on the antennse of the young larva are absent in 

 the exuviae). Ocelli small, reniform, inconspicuous, placed in a 

 triangle between the eyes. Labuitn enormous, measuring 6*2 mm. 

 by 4'8 mm. when folded; perfectly flat underneath and project- 

 ing in front somewhat beyond the upper parts of the head, and 

 backwards well past the procoxee, so as to cover most of the 

 underside of the prothorax ; inentum rather shield-shaped, 

 furnished with a set of small stiff" spines on eacii side, and pro- 

 jecting slightly forward in front in a rounded curve with slight 

 median indentation; no setse pre.sent; lateral lobes strong, rather 

 narrow, with several small spines on the outside along the basal 

 portion; terminating in a sharp slender movable hook and in 

 three smaller fixed spines or hooks; of these the middle one is 

 the largest, and below its base is a much smaller one; the third 

 lies behind and between the movable hook and the larger fixed 

 hook (see Plate xxxiii., tig. 2). Prothorax well developed, rounded 

 above; procoxae set well forward under the head; forelegs exceed- 

 ingly strong and large, femora broad, smooth, and flattened; 

 tibise straight, smooth, and narrow; tarsi short, three-jointed, 

 ending in two strong claws. Meso- and metathorax almost as 

 wide as head; smooth, strongly built but not large; middle- and 

 hind-legs also strongly built, with flattened femora. In the 

 position of rest, the fore-legs are projected well forward and 

 pressed close to the rock; the labium also presses close to the 

 rock; the femora of the middle-legs lie almost flat, but those of 

 the hind-legs are held with the broad flat sides nearl}^ vertical; the 

 whole position suggests that the insect lies concealed by clinging 

 flat against the rock, and is ready to spring forward at its prey 

 at any moment. Measurements of femora, tibise and tarsi of 



