xii. Intrnduction 



the preceding region there does not appear to be much difference, but 

 dust storms are more frequent and add to the discomforts of the hot 

 season. 



The above partition may not perhaps be quite m accordance with 

 the views of some travellers and authorities on the subject, and is of 

 course open to criticism, but in the main I think it may be taken to 

 be fairly correct. 



Some writers, M. Fernand Lataste among them (Expl. Hcient. de 

 la Tunisie, p. xiv.), have ehminated the Central zone entirely, on the 

 ground that no Hants Plateaux exist in Tunisia. This I need hardly 

 say is a mistake, for although the high plateaux may be limited and 

 less in extent than in Algeria, tliey certainly are to be found in 

 the west of Tunisia, and extend like terraces, gradually diminishing in 

 elevation, almost to the Chott district. Apart from this, however, 

 there are other extensive tracts of country in the Central Tunisian 

 region, which differ in their character both from the country north 

 of the Atlas and from the southern desert districts. It is true that 

 the Central region comprises such districts as the Sebka Sidi-el-Hani 

 and the Sebka-el-Melah, which in character undoubtedly belong to 

 the Chott region, but these districts are limited in extent and cannot 

 be taken as representing the greater part of Central Tunisia. 



With regard to the Ornis of the several regions mentioned, each 

 appears to have certain species which are either peculiar to that par- 

 ticular region or are more abundant m it than in the other regions. 

 Besides this, in the case of some of the resident species, such as the 

 Crested Larks, for instance, different forms of the same species are to 

 be found in the different regions, the variation of these forms being in 

 some cases considerable, and not always limited to the coloration of 

 the plumage alone, but occasionally extending to the structural parts 

 of the birds. The Crested Larks undoubtedly afford a striking 

 example of the extent to which local variation may be carried by 

 natural causes, and no country probably affords a better opportunity 

 of observing and studying this interesting subject than Tunisia. 



The Larks, as a family, are remarkably well represented in this 

 country, their sole rivals being perhaps the Chats, especially in some 

 of the southern districts of the Eegency, where these two families 

 are often the only birds to be met with. 



It may at first sight appear somewhat curious that of these two 

 families of birds, both .so well represented in this country, one, that 



