BY R. J. TILLYARD. 95 



In the position of rest, these gills are held in the same manner 

 as those of Isosticta (see Text-fig. 2 3). 



The three Australian genera having nodate gills may be 

 separated as follows : — 



Node situated well before lialf-way. Distal portion of gill with the 

 well-rounded tip not enlarged. Inner edge of gill with spines 



suppressed, except at extreme base 



1. Ca/m.7/70« Tillyard; (PI. ii., fig.l2). 



Node situated at about half-waj'. Distal portion of gill considerably 

 widened towards tip. Inner edge of gill with spines present up 

 to nodal line 2. 



I Tip quite rounded. 8pines of the inner edge slender, nnich smaller than 

 those of the outer edge Pseudagrion 8elys; (PI. ii., fig. 13). 

 'J. -, Tip with a tiny sharp point. Spines of the inner edge stout, almost as 



large as those of the outer edge 



' A uMroaffvion Tillyard ; (PI. ii. , fig. 1 4). 



The following are short descriptions of the gills of the known 

 larvfB : — 



1. Caliagrion hillmghnrsti Martin. Length of gills when full- 

 grown, median 8*5, laterals 8 -5 mm.; median gills slightly broader 

 than laterals, and slightly bent at node. Nodal spines enor- 

 mous; nodal line oblique from outer edge to rachis, thence to 

 inner edge either transverse or slightly inclining distad. Colour 

 of gills either bright green, or orange-pink (apparently according 

 to the colour of the leaves of the reed on which the larva dwells). 

 Pigmentation very beautiful, arranged as shown in Plate ii., fig. 12, 



2. Pseudagrion australasw Selys. Length of gills when full- 

 grown, median 6 mm., laterals 6 mm., median broader than 

 laterals. Nodal spines large; nodal line oblique right through 

 to inner edge. Colour of gills usually rich brown, more rarely 

 greenish or yellowish; pigmentation in dark brown, as shown in 

 Plate ii., fig. 13. 



3. Pseudagrion aureofro7is Tillyard. Very similar to those of 

 Ps. australasice, but shorter (5mm. when full-grown); colour pale 

 yellowish-brown, with less distinct pigmentation. 



4. Austroagrion cyane Selys. Length of gills when full-grown, 

 median 3'7 mm., laterals 4 '3 mm., median broader than laterals. 



