ROCK GROUS. 485 
nearly equal, the inner being a little longer. Claws slightly arched, 
depressed, broad, with thin edges and rounded at the tip. 
Plumage compact, the feathers generally ovate and rounded ; those 
on the tarsi, toes, and soles oblong, with loose stiffish barbs. Wings 
rather short, concave; the primaries strong, narrow, tapering, pointed ; 
the first an inch and seven-twelfths shorter than the second, which is 
four-twelfths shorter than the third, this being the longest, but only 
exceeding the fourth by a twelfth anda half. Tail rather short, nearly 
even, of sixteen broad feathers, of which two are incumbent, less strong, 
and longer than the rest by two-twelfths of an inch. 
Bili black ; superciliary membrane scarlet ; claws dusky, towards 
the end yellowish. The plumage is pure white, with the exception of 
a broad band of black from the upper mandible to the eye, and for a 
short space behind it; the shafts of the six outer quills, which are 
brownish-black, and all the tail-feathers, the two middle excepted, they 
being of a deep greyish-black colour, with a terminal narrow band of 
white. 
Length to end of tail 133 inches, to end of wings 12; wing from 
flexure 8; tail 43; tarsus 1,% ; hind toe 4, its claw ;% ; middle toe 43, 
its claw 75. 
Male in Summer. Plate CCCLXVIII. Fig. 2. 
In summer, the plumage differs little in texture, with the exception 
of that on the feet, which is short and thin on the tarsi, worn on the 
base of the toes, of which the soles and half of the upper surface are 
denuded. The bill and claws are of the same colour as in winter ; but 
the plumage is variegated with black, reddish-yellow, and white. The 
upper parts may be described as black, transversely and irregularly 
banded and spotted with yellowish-red, the feather terminally mar- 
gined with white, there being on each feather several bars of yellowish- 
red running from the margin inwards, but leaving a black space in the 
centre. ‘The lower parts are lighter, more broadly and regularly barred 
with brownish-black and light reddish-yellow. The feathers along the 
edge of the wing, the alula, primary coverts, nearly all the secondary 
coverts, primaries and outer secondaries, white ; as are the lower sur- 
face of the wing, the axillar feathers, and some of the feathers on the 
abdomen, as well’as those on the feet, the latter being soiled or tinged 
with yellowish or grey. ‘The shafts of the primaries are brownish- 
