OBSERVATIONS ON FALCO HENDERSONI, HUME. 49 



The article I have referred to is as follows : — 



" 13.— Falco Hendersoni, Hume. 

 " Socol Hendersona. 



" Falco Hendersoni, Henderson and Hume, Lahore to Yar- 

 kand, pi. 



" The various stages of plumage, according to age and local 

 variation, make it very difficult to distinguish the different 

 species of Falcons ; so much so, that even the best ornitholo- 

 gists differ in this respect in their opinions. To one of such 

 disputed species belongs Falco sacer, which forms several varie- 

 ties in eastern Europe and throughout Asia. In the regions 

 of our travels, we did not observe (or at least did not obtain) 

 the true Falco sacer, Schleg., which is so beautifully figured by 

 Schlegel in his Traite de Fauconnerie, pi. V., and by Gould 

 in his ' Birds of Asia,' Part XX. Everywhere we found 

 only the species described by Hume, in ' Lahore to Yarkand' 

 under the name of Falco Hendersoni. We obtained only four 

 specimens ('two males and two females), of which (two males 

 and one female) completely correspond with Hume's descrip- 

 tion, with only insignificant differences. The second female 

 which is rather } r ounger than the three former specimens (this 

 is to be distinguished by the blue and not yellow legs), differs 

 from them by the absence of a fully striped tail, as only in- 

 complete reddish yellow bands are perceptible on the inner 

 webs of the tail feathers, whilst the outer webs are marked 

 with spots of the same colour as the bands. Again, the yellow 

 streaks of the female F. Hendersoni are replaced in the present 

 specimen by spots of the same colour. The breast is pied, on 

 account of the large dark brown spots, just like the true F. 

 sacer ; whilst on F. Hendersoni, as also on our three speci- 

 mens, the breast is milk white, marked with narrow and tri- 

 angular small spots. The bill is black at the point, and bluish 

 at the base, and has only on the lower mandible a yellow 

 mark, which colour is predominant on both mandibles in our 

 three specimens. Consequently the young plumaged F. Hen- 

 dersoni is nearer to F. sacer, which, however, is sufficiently 

 developed to be separated as a species. 



Measurements : — 



Length. Width. Win^. Tail. Gape. Tarsus. Middle toe. 



<J 18-5 33 148 7-8 123 19 178 



? 225 37 166 93 127 216 20 



" Henderson's Falcon was found by us wherever we went, 

 from Kiachta down to the sources of the Yantze-Kiaug ; but 

 it was most numerous in winter in the Zachar country and 



