Grey Shrikes of Tunisia. 229 



of the Atlas (the true habitat of L. algeriensis) , as well as of 

 that of the serai-desert regions bordering the Tunisian 

 Sahara, where L. elegans occurs. Its altitude is compara- 

 tively insignificant, being only a few hundred feet above 

 sea-level, and very much below that of the High Plateau to 

 the north and north-west, although always higher than the 

 depressed plain of Kairouan and the low-lying country 

 further east. Fairly well watered in winter and spring, this 

 district has a tolerably luxuriant vegetation, vast stretches of 

 corn-land occurring, interspersed witli olive -groves, and 

 plentifully dotted over with clumps of thick bushes, chiefly 

 of Zizyphus, Lotus, and other thorny plants. 



As stated in my 'Notes,' on comparing the specimen of 

 doubtful Grey Shrike obtained from South Tunisia with 

 examples of L.fallax in the British Museum, I found it agree 

 so closely with some of them that I determined to refer it to this 

 species. Having, however, now obtained similarly-plumaged 

 birds from a district in Central Tunisia which may be 

 considered the meeting-ground of the two species L. algeri- 

 ensis and L. elegans, I am inclined to look upon the<e 

 birds as being either hybrids between the two species, or 

 else as belonging to intermediate forms modified according 

 to the natural characteristics of the localities where they 

 may occur; in any case I think it evident that they should 

 not be referred to L.fallax, admitting this to be a good 

 species, which is perhaps open to doubt. 



Which of the two theories I have just mentioned may be 

 the correct one I am not prepared to say, although the 

 balance of evidence is perhaps somewhat in favour of the 

 former. The theory of hybridism, unentertainable as it might 

 be in certain cases, is certainly not improbable in a case 

 like the present, where the two species in question are so 

 closely allied, and where no sufficient natural boundary or 

 division exists to keep them apart, for the Atlas JNIountaius 

 in Tunisia do not form the same unbroken barrier that they 

 do further west. 



In favour of this theory, moreover, are the following facts : 

 firstly, that, so far at any rate as I have been able to as- 



