292 FALCO GYRFALCO. 



timious, or not opposing each other, whilst they are continuous 

 in the young F. Groenlandicus." The distinctive characters 

 which he assigns to the adult of these species are the follow^ing : 



Falco Islandicus. Ground of the upper plumage a dark lead 

 or mouse colour, barred and spotted with cream colour ; (on 

 the) under parts the ground is buff, marked with streaks, 

 heart-shaped spots, and bars of dark mouse colour. Wings 

 reaching to within about li in. of the end of the tail. Adult 

 male 1 foot 9 in. ; extent of wings 3 feet 10 in. Adult female, 

 length 1 foot 11 in. ; extent of wings 4 feet 2 in. 



Falco Groenlandicus. Ground of the plumage pure white ; 

 upper parts elegantly marked with arrow-shaped spots of a dark 

 grey ; under parts and head streaked with the same ; wings 

 reaching to within 2 inches of the end of the tail ; second pri- 

 mary the longest. Adult male, length 1 foot 9 in. Adult 

 female, length 1 foot 11 in. ; extent of wings 3 feet 10 in. 



It is further stated that all the mature specimens from Ice- 

 land seen by the author, amounting to seven, have the upper 

 mandible furnished with two processes, whilst in the many 

 Greenland specimens examined, only two had the double pro- 

 cess, and these were apparently very old individuals. 



Without expressing any decided opinion upon the subject, I 

 have to observe that analogically the alternation or continuance 

 of the bars on the two middle tail-feathers is of no value as a 

 character ; for, having examined a great number of skins of 

 Falco Tinnunculus, Falco ^salon, Buteo vulgaris, Cuculus 

 canorus, Eudynamis orientalis, and several other species having 

 numerous bars on the tail, I find that in all of them the bars 

 are sometimes continuous and sometimes alternating. In the 

 Snowy Owl, the bird which most resembles the Gyr Falcon 

 in its style of colouring, the bars are either direct or alternate. 

 Unless therefore every one of these species is composed of two, 

 there is no reason to believe that this character is sufficiently 

 distinctive in the case of the Gyr Falcon. In the two adult 

 *' Greenland Falcons," one of which, however, was from Ice- 

 land, and that upon unquestionable authority, the festoon or 

 second tooth was conspicuous, while in the younger individuals 

 it is scarcely apparent. As to the diflference of half an inch in 



