BY R. J. TILLYARD. 735 



Hah. — Mountain-brooks, Armadale, Waroona, Bridgetown; 

 exceedingly abundant at Wilgarrup and Margaret River; Dec- 

 ember-February. 



This fine but ver}^ black-looking insect is a splendid flyer, 

 skimming swiftly over the running streams, or dodging in and 

 out of the overhanging herbage at great speed. Sometimes they 

 will hover almost motionless over a pool for a long time or travel 

 slowly up and down in search of prey. On hot summer days 

 they may be seen dashing about at great speed in almost bewil- 

 dering succession, especially towards evening. This species, to 

 which I have given the name anacantha because of the absence 

 of the large dorsal spike on segment 10 of the male, is very closely 

 allied to A. parvistigma and A. multi'punctato. of the Eastern 

 States. The males may be at once distinguished by the absence 

 of the spine referred to, and both sexes by the comparative 

 minuteness of the spots on the thorax and abdomen. In the 

 evenings it settles in the dried undergrowth of the " black-boys," 

 or sometimes on the trunks, or on the trunks of trees and bushes; 

 and in such a position its protective colouring renders it exceed- 

 ingly difficult to discover. It is easily disturbed, and dashes off 

 at lightning speed. It is not easy to capture. 



None. 



Family CALOPTERYGID.E. 



Family AGRIONID.^. 



19, Argiolestes minimus, n.sp. 



(Plate XXXV., figs. 11-12.) 



^. Very variable in size, the commonest form being : — total 

 length 32-34 mm., abdomen 26-27 mm,, forewing 21mm., hind- 

 wing 20 mm. 



Wings: Neuration black. Pterostigma 13, white in the 

 young insect, but gradually darkening to brown or even black in 

 the mature insect. Nodal Indicator 

 black; epicranium black, shading to 



2 9-14 

 2 9-12 



Head: Eyes 

 dull grey near 



eyes and postclypeus; postclypeus dark grey; anteclypeus black, 



