298 Rev. H. 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 ' weds ' or dry ravines of the 

 M'zab country. 



35. DROMOLiEA LEUcocEPHALA (Brchm, 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 tbeii' respective sides. No doubt the scarcity of their insect 



