Mr. J. I. S. Whitaker on Tumsiuii B'uuh. 101 



Larks to be met with in Tunisia^ aud which might perhaps, 

 for convenience' sake, be briefly divided into three classes or 

 races, the northern, southern, and desert races, the differ- 

 ence seems to be solely one of plumage-colour, varying 

 according to the natural characteristics of the localities in 

 which the different forms occur. Thus, in the case of the 

 northern form, which inhabits regions where the climate is 

 almost European, with abundant moisture and vegetation, 

 and where the soil and surroundings generally are of a more 

 sombre hue than further soutli, the general tone of colour is 

 darkish, or a grey-brown. In the southern form, which 

 inhabits districts where the climate is drier, where vegetation 

 is scanty, and the country more arid, we have a lighter or 

 buff shade of colour ; while in A. isabellina, to be found only 

 in the far south, and in actual proximity of the desert, the 

 plumage is still paler and of an isabelline hue. The transi- 

 tion, or variation in plumage-colour, however, seems to 

 be gradual aud uninterrupted, and the impossibility of any 

 delimitation, or of positively fixing the limits of each zone, 

 is apparent, as we should find more difference between indi- 

 viduals of the same zone but extreme opposite limits than 

 between individuals of different zones but adjoining limits; 

 for instance, we should find more difference between a speci- 

 men obtained from the extreme north and one obtained 

 from the extreme south of the northern zone, than we should 

 between the latter and one from the extreme north of the 

 southern or adjoining zone. An interesting exception to the 

 general change in plumage-colour between the three forms 

 is noticeable in the tail-feathers, which, with the exception 

 of the centre ones, maintain the same shades of colour 

 throughout the entire transition. 



I have examined a good series of all the three forms of 

 which I have spoken, and I am inclined to think that there 

 is quite as much reason to divide the northern and southern 

 races as there is to separate the desert form A. isabeUina, 

 although perhaps one would not think so at first sight, or 

 when comparing merely extreme types. 



Dealing with these three forms of Crested Larks one 



