148 BIRDS OP TUNISIA 



the base of the bill to behind the eye ; back olive-green ; rump and upper 

 tail-coverts slightly brighter green, the latter vvith blackish centres to the 

 feathers ; quills dark brown, secondaries and wing-coverts broadly margined 

 with yellowish-white and buff; the two outer pairs of tail-feathers white, 

 with a diagonal blackish margin on part of inner web, the remaining tail- 

 feathers blackish-brown ; chin and a line below the lores white ; throat 

 and entire under surface of body bright canary-yellow, slightly tinged with 

 dull green on sides. 



Iris, bill and feet very dark brown. 



Total length 6-25 inches, wing 3'35, culmen -55, tarsus 1. 



Adult female rather duller in colour than the male and slightly 

 smaller. 



Young birds have the upper parts olive-brown, the rump and upper tail- 

 coverts greener, the underparts buffy-white, tinged with pale yellow on 

 abdomen and crissum, and the fore-neck with a collar of brown spots. 



Observatio7is. — Mo&t of the Yellow Wagtails at times show a few blackish 

 or dark greenish feathers on the breast, these dark markings occasionally 

 becoming more developed. The white eyebrow of the present species is 

 not unfrequently tinged with yellow. 



Varieties are sometimes met with in the various forms in which the 

 yellow underparts have a distinct orange hue. 



Specimens may occasionally be found with an admixture of yellowish- 

 green feathers on the crown. I have one such specimen from South Tunisia 

 and there are similar examples in Mr. J. H. Gurney's collection from South 

 Algeria. 



The Yellow Wagtails, the group to which the present species 

 belongs, were separated by Cuvier from other members of the family 

 under the generic name of Biuhjtes, but the grounds for such separa- 

 tion being somewhat slender, the subdivision has not been generally 

 accepted by modern authors, many of whom consider it advisable to 

 retain the group under the genus Motacilla. 



As most ornithologists must have had occasion to observe, the 

 group is a difficult one to deal with, owing to the number of forms 

 which it presents ; and the separation or subdivision of these, with 

 our present limited knowledge regarding some of them, is no doubt 

 more or less a matter of opinion. 



Treating of those which occur in the Tunisian Eegency, I may 

 briefly say that the following forms are to be found, which in their 

 fully adult and typical plumage may be thus characterised, viz. : — ■ 



(a) M. flava : with a bluish-slate-coloured crown, a distinct white 



