BY R. J. TILLYARD. 573 



to prothorax; sides with a straight oclireous band bordered above 

 by steely black; a small round yellowish spot and an elongate 

 yellowish patch very low down; notum black, scutella yellow. 

 Leys black . Abdomen very slender, 1-2 swollen, 3 very slender, 

 then widening from 4 to 6, 6 to 8 tapering, 9-10 narrow. Colour 

 black, Avith yellowish spots as follows : — 2, a pair of very small 

 round central spots ; auricles yellowish-brown : 3, a pair of 

 triangular basal spots, and two small central spots touching 

 dorsally : 4, a pair of very small basal spots, and a pair of central 

 spots touching dorsally, larger than in 3 : 5, a trace of basal spots, 

 a pair of round dorsal spots two-fifths from base, larger than in 4; 

 6-8, a pair of round dorsal spots near centre, decreasing in size 

 from 6 to 8; all central spots crossed by the fine transverse black 

 line of the supplementary carinfe : 9-10 black, 10 swollen basally 

 into a rounded dorsal tubercle. Appendages: superior 

 3-8 mm., black, slender, first three-fourths straight, converging, 

 last quarter turned slightly inwards; tips rather blunt. Inferior 

 2 mm., semitransparent brown edged with black; narrow sub- 

 triangular, upcurved. The superior carry a large inferior spine 

 at bases (Plate Ixii., figs.l5, 16). 



Hab. — Waroona, W.A., taken by Mr. G. F. Berthoud; January 

 27th, 1912. 



T y p e : (J, Coll. Tillyard. 



This is the most interesting Synthemid yet discovered, for it 

 combines in itself characteristics of the two genera Synthemis and 

 Metathemis, and probably represents, fairly closely, what the 

 immediate ancestors of our East- Australian Metathemis were like, 

 before they evolved to their present condition. The known species 

 of Metathemis are very closely allied, and, at a not very remote 

 period, were probably represented by only one form, which may 

 have been the same in Eastern and Western Australia. After 

 the great desert baiTier arose, the Western form seems to have 

 barely held its own, and is now only represented by this single 

 rare species; while, on the other hand, the Eastern form spread 

 far and wide, and altered considerably in the process. Tliough 

 Syrithemis spiniger is generically a true Synthemis, possessing the 

 peculiar shape of the abdomen and the long appendages of that 



