1920.] 



(\f the Mnroccan " Middle-Alias." 



285 



slightly influenced racial dislribution in Mauretiinia; Init 

 for myself I think it cannot have been drastic enongh to be 

 of much account, and that we must here seek the real 

 explanation of all such problems in natural causes. 



Note: T consider the much-quoted case of the Bermudan 

 (introduced) rxoldtinch is a|)t to mislead, and see in it no 

 more of a guide to the rate of Variation in Nature than you 

 get from a tew generations of "' fed "' AVild-ducks. 



The following- table oives the variety of racial forms of 

 the six selected typical woodland-species that inhabit the 

 forest-areas in question : 



RACES (Siibspecific name abbreviated). 



Grcoi at. Spotted 

 Localiij/. Jai/. Creeper. Nuthatch. Coat-tit. If'oodpeclei: Wnodpecler. 



S. Spain klein. ultra. 



Riff whit. ? 



Woods of the Plain 



(Forest of Mamora). 



Middle- Atlas oenops manr. 



Great-Atlas oenops maur. 



Mts. of Tlemcen whit. maur. 



Algerian Tell cerv. maur. 



Saharan Atlas 



(Djelfa forest) oenops ? maur. 



Aures Mts cerv. maur. 



Tunisian Mts cerv. maur. 



Note : — = Species does not exist, 



?= „ may exist. 

 r(name)= •„ does exist and is prohnbly (name). 



A satisfactory ex{)lanation of these distributional 



problems is beyond my powers, and indeed will scarcely 



be possible until much more material in all departments 



of Zoology is available, but in Plate XI. I have endeavoured 



to suggest certain lines of thought for the consideration of 



those interested in tiie subject. 



