OWLS AND DIURNAL BIRDS OF PREY. 373 
quietly from above. The members of the group vary from 
medium to small size. They are all neatly built with long 
pointed wings. The second quill-may be the longest, as in the 
genera Falco and Erythropus, or the second and third quills 
may be almost equal, thus giving the wing a slightly more 
rounded appearance, as in salon and Tinnunculus. The 
bill is stout, shortish, and well hooked, with one conspicuous 
tooth on each side of the upper mandible, and with more or 
less of a festoon further back. The nostril is circular with a 
central tubercle. The tarsus is fairly short, with the upper 
half plumed in front; the toes are long; the claws curved 
and sharp. The tail is of moderate length, and is slightly 
rounded in all our genera, except the Kestrel, in which it 
is more fan-shaped, the outer tail feathers being markedly 
shorter than the central pair. 
Rough Key to Group. 
A.—Second primary longest ; first primary much longer 
than fourth. 
(a) Sexes similar ; legs yellow. Genus Falco. 
(1) Length 16-19; crown dark gray; breast only 
slightly rufous. 
F’. peregrinus (Peregrine Falcon). 
(2) Length 15-18; crown blackish; breast gene- 
rally dark rufous. 
F’, peregrinator (Shahin Falcon). 
(3) Length 10°5-11°5. 
F.. severus (Indian Hobby). 
(6) Sexes dissimilar ; legs deep orange-red ; length 
about 12. 
Erythropus amurensis (Kastern Red-legged 
Falcon). 
B.—Second and third primaries longest ; first primary 
about equal to fourth. 
(1) Tail only slightly rounded. 
Asalon chicquera (Red-headed Merlin). 
(2) Tail graduated, outer feathers distinctly shorter 
than inner pair. 
Tinnunculus alaudarius (Kestrel). 
9 6(21)20 
