GYR FALCON. 291 



and the lower tail-coverts with only the shaft and a narrow 

 oblong space toward the end dark. 



Length to end of tail 21 inches ; wing from flexure 15 ; 

 tail 9 ; bill along the ridge Ij ; tarsus 2^^^ ; middle toe 1{|, 

 its claw 1. 



Progress toward Maturity. — In the next stage, as it 

 would appear, the upper parts become of a more uniform 

 bluish-grey, most of the whitish spots having disappeared from 

 the back, and upper part of the head. Of this kind were the 

 two birds figured by Mr Audubon, and obtained by him in 

 Labrador, as mentioned above. Li this state also I have exa- 

 mined the skin of a female from Shetland. In one of these 

 the light bars on the tail had nearly disappeared ; but in the 

 two females they were quite distinct, and those on the middle 

 feathers opposite, though not continuous. In the Shetland 

 specimen, which is apparently a female, its length being twenty- 

 four inches, the lower parts are yellowish-white, with longitu- 

 dinal oblong, brownish-grey spots ; the upper parts slate-grey 

 tinged with brown, the feathers margined with paler ; the bill 

 light blue, dark at the tip, and yellowish at the base ; the feet 

 blue, but with the edges of the scutella yellowish. 



Dr Richardson, who no doubt has had opportunities of ob- 

 serving the changes which take pla je in the colouring, says : — 

 " The young Gyr-falcons show little white on their plumage, 

 being mostly of a dull brown colour above. As they grow 

 older, the white margins encroach on the brown, which be- 

 comes merely a central blotch, indented on each side by the 

 white ; while in aged birds the plumage is mostly pure white, 

 varied only by a few narrow transverse bars on the upper parts." 



Remarks. — Mr Hancock, in a paper read to the British As- 

 sociation, and published in the Annals of Natural History, Vol. 

 II. p. 24'1, is decidedly of opinion that two species have been 

 confounded under the synonymous appellations of Jer or Gyr 

 Falcon and Iceland Falcon. Both species, Falco Islandicus 

 and Falco Groenlandicus, he says, are precisely similar in their 

 first plumage, with this exception, that the young F. Islan- 

 dicus has the bars on the two middle tail-feathers " non-con- 



