FALCO HYPOLEUCUS, Gould. 
Grey Falcon. 
Falco hypoleucus, Gould in Proc. of Zool. Soc, Part VIII. p. 162. 
Boorh-ga, Aborigines of Moore's River in Western Australia. 
Of this rare and beautiful Falcon I have seen only four examples, three of which are in my own collection, 
and the fourth in that of the Earl of Derby. The specimen from which my description in the "Proceedings 
of the Zoological Society " was taken, was presented to Mr. Gilbert by Mr. L. Burgess, who stated that he 
had killed it over the mountains, about sixty miles from Swan River ; subsequently it was obtained by 
Mr. Gilbert himself in the vicinity of Moore's River in Western Australia ; and my friend Captain Sturt had 
the good fortune to secure a male and a female during his late adventurous journey into the interior of South 
Australia. "They were shot at the Depot on a Sunday in May 1845, just after service; they had been 
soaring very high, but at length one descended to the trees on the creek, and coming within range was 
shot ; when the other proceeding to look after its companion was also killed. It must be a scarce bird, for 
no others were seen." 
The acquisition of the Falco hypoleucus is highly interesting, as adding another species to the true or 
typical Falcons, and as affording another proof of the beautiful analogies which exist between certain groups 
of the southern and northern hemispheres; this bird being as clearly a representative of the Jerfalcon 
of Europe, as the Falco melanogenys is of the Peregrine, and the Falco frontatus of the Hobby ; but as I 
have more fully entered into this subject in my observations on the genus, it is unnecessary again to detail 
them here. 
The adult has the whole of the upper and under surface and wings grey, with a narrow line of black 
down the centre of each feather ; a narrow ring of black nearly surrounding the eyes ; primaries brownish 
black, which colour assumes a pectinated form on a mottled grey ground on the inner webs of those 
feathers ; tail-coverts grey, barred with brownish grey ; tail dark brownish grey, crossed with bars of dark 
brown ; irides dark brown ; cere, orbits, gape, base of the bill, legs and feet brilliant orange-yellow ; the 
yellow becoming paler from the base of the bill, until it meets the black tips of both mandibles ; claws black. 
The young birds have the upper surface mottled brown and grey, and the under surface nearly white, and 
more strongly marked with black than in the adult. 
The Plate represents the two sexes of the natural size. 
