298 
Rev. XL B. Tristram on the 
Brehm received his birds from Nubia. This species differs from 
D . leucura in having the whole tail white, with the exception 
of the lower portion of the two centre feathers, while the vent 
and the lower portion of the back are snowy white to the extent 
of three inches from the extremity of the tail. The whole of the 
rest of the plumage is glossy black, instead of the rusty colour 
characteristic of _D. leucura ; and the bird is in all its propor¬ 
tions more slender and a little smaller. In its habits it no way 
differs from its congener. It never approaches the north of the 
Sahara, and is strictly confined to the f weds * or dry ravines of the 
M'zab country. 
35. Dromol^a leucocephala (Brehm, Journ. f. Orn. 1858, 
p. 62). (White-headed Rock-Chat.) 
This bird I also procured in considerable numbers in the 
southern portion of the Sahara in 1856. It was first described 
by Brehm in 1858, from Nubian specimens. I have compared 
mine with one of Brehm's type specimens, and the only distinc¬ 
tion I can perceive is that the white of the Algerian bird extends 
a little higher up the back. It only differs from D. leucopygia 
in having a snow-white head. There is a narrow band of black 
just above the nostrils extending over the eyes. The rest of the 
forehead, crown, and down to the nape of the neck are white. The 
whole under-plumage glosssy black to the vent, which, with the 
under tail-coverts and the extremity of the feathers about the 
thighs, is snow-white. Neither in this nor the preceding bird 
is there the slightest difference between the sexes in plumage. 
This Rock-Chat has a further range east and west than D. 
leucopygia, and is far more abundant in its localities, but does 
not come so far north. Closely as it resembles it, I never ob¬ 
served the two species together. It is very pugnacious, and 
lives all the winter in pairs, each couple preserving its own 
domain undisturbed. I have watched a male perched on a point 
of a rock, with his white tail expanded like a fan, and perfectly 
erect, whistling loud defiance to a rival at the other side of the 
ravine. The challenge is speedily taken up, and they advance 
nearer each other, till, after a very short encounter, they retire 
to their respective sides. No doubt the scarcity of their insect 
