50 BIRDS OF TUNISIA 



S. litgens is of a darker rufescent hue than it is in S. hcdophiht, in 

 which latter species it is sometimes ahuost pure white. Besides the 

 difference in the colouring of the crissum and under tail-coverts, 

 however, there is also a certain difference in the relative size of the 

 two species ; adult males, showing an average wing-measnrement of 

 3-75 inches in S. lugens against 350 inches in S. halophila. In hoth 

 species the females are slightly smaller than the males, and perhaps 

 this forms the only external means of distinguishing between the 

 sexes of S. lugens. 



Canon Tristram, during his travels in Algeria, appears to have met 

 with adult males and females, as well as with immature males of the 

 present species. The adult males he referred to S. lugens, Licht., but 

 the females and the immature males he took to be belonging to a 

 new species, and called them Saxlcola hahphila {Ibis, 1859, pp. 59 

 and 300). This being the case, his name, although given in ignorance 

 of the real state of matters, must stand. 



Both Dr. Koenig (./. /. 0. 1895, p. 376) and Baron Erlanger (././. 0. 

 1898, p. 231) have entered at some length into the question of this 

 interesting discovery, and the former has given some good plates of 

 the species, showing plainly the difference between the adult male 

 and female, and a very old female. The peculiarly silky texture of 

 this Chat's plumage, alluded to by Canon Tristram, is well shown in 

 these plates. 



Seebohm, when describing the female of S. lugens (Cat. B. Brit. 

 Mus. V, p. 371) as quite different from the male in plumage, must 

 have had before him specimens which were not from Egypt but 

 probably from North-west Africa. Loche (" Expl. Sclent. Alg. Ois." i, 

 p. 207) appears to have noticed the difference between the sexes 

 of the present species, but did not distinguish ,S'. Iialopliiht from 

 S. lugens. Mr. C. Dixon also seems to have noticed, and called 

 attention to the difference between the sexes of the two species {Ibis, 

 1882, p. 562). Mr. Dresser's plate of immature so-called S. erijthrcea 

 (Birds Eur. ii, pi. 29) shows the types of Canon Tristram's S. halophila. 

 It is a pity Mr. Dresser did not avail himself of the opportunity 

 afforded him, when publishing the Supplement to his " Birds of 

 Europe," to correct certain errors regarding some of the Chats which 

 appeared in his above great work. 



With regard to the range of 8. halophila, so far as it is at present 

 known, it extends throughout the Algerian and Tunisian Sahara, and 



