THE BIEDS OF AUSTRALIA. 
the Falconid* we follow, places the subfamily CifcincB much nearer to the 
CircaetincB (containing Spilornis) than has been the custom of other authors.” 
This led me to look up the species of Spilornis, a genus foreign to the 
Australian fauna, but living to the North, in the Philippines, etc., and I 
found species with the under-parts exactly similar to the strangely coloured 
Circus assimilis. To me this suggested relationship: as structural characters 
in these birds appear to be more recent than coloration, as is seen in the case 
of species of Accipiter and Astur. Reference to Pycraft’s paper shows that 
from osteological features Gurney’s arrangement has been confirmed, as there 
the Circinse come practically next to the Circaetinse as follows: “The 
Circaetinse include GircaMus, Geranospizias, Helotarsus and Spilornis. Closely 
allied, and intermediate between it and the next subfamily — the Circinse — 
comes the highly-specialised Polyborinse. It seems to me that this sub- 
family might perhaps as well be included in the Circinse, with which, as 
Dr. Suschkin shows, it has many characters in common, and in this I can 
confirm him. The Circinse embrace Circus, Geranospizias, JJrotriorchis and 
Strigiceps.’^ It is (|uite possible that specimens of Circus assimilis were not 
available, or if at hand, comparisons were not instituted between them and 
Spilornis, as no mention is made of species^ group names simply being cited. 
It will be interesting to investigate the osteology of Circus assimilis in this 
connection. 
CIRCUS APPROXIMANS OOULDI. 
16 
