94 CHARLES DARWIN. 



the desert has been produced by the survival of 

 the lightest coloured individuals, Galerida ahyssinica 

 only differing in this respect from G. cristata of 

 Europe. Short-billed species of the same genus 

 inhabiting hard rocky districts, and long-billed 

 inhabiting loose sandy tracts have, he believes, been 

 produced by the survival in each case of the forms of 

 bill most suited to procure food : 



" Here are only two causes enumerated which might serve 

 to create as it were a new species from an ol.d one, yet they 

 are perfectly natural causes, and such as, I think, must have 

 occurred, and are possibly occurring still. We know so very 

 little of the causes which in the majority of cases make species 

 rare or common, that there may be hundreds of others at 

 work, some even more powerful than these, which go to 

 perpetuate and eliminate certain forms 'according to natural 

 means of selection.' But even these superficial causes appear 

 sufficient to explain the marked features of the Desert races, 

 which frequently approach so very closely the typical form, 

 and yet possess such invariably distinctive characteristics, that 

 naturalists seem agreed to elevate them to the rank of 

 species." 



Although the author also declares his belief in the 

 special creation of many species — a view put forward 

 as possible by Darwin in the "Origin"^ — and also 

 believed in some direct influence of locality, climate, 

 etc., the above quoted passages are a most complete 

 acceptance of natural selection, at the same time 

 affording excellent examples of its operation. 



* " There is grandeur in this view of life, with its several powers, 

 having been originally hreathed by the Creator into a few forms or 

 into one ; . . ." — (Con eluding paragraph of " Origin," I860, p. 490.) 



