484 Letters, Announcements, ^c. 



explained by the facility or difficulty of sustaining existence 

 in vaiying localities. On similar principles we may account 

 for the existence of such a bird as Galerida macrorhyncha in 

 the warm^ genial climate of the Oases, where, winter being 

 unknoAvn, and food always abundant and close at hand, every 

 stimulus is afforded to a vigorous development, while its prey 

 being generally hidden in the soft open mould of the gardens 

 and barley patches, any tendency to elongation of the bill is 

 fostered and encouraged, until we find a race two inches 

 longer than Galerida isabellina, and with a bill exactly double 

 in length (1 inch instead of 'S). 



" A process precisely similar may be supposed to have deve- 

 loped the various species of Desert Chats, until we find in 

 the desert of Souf that all distinctive trace of colour has been 

 scorched out, and instead of the brightly clad Saxicola sta- 

 pazina, we have no more cheerful representative of the genus 

 than >S. homochroa. Widely as these two extremes apjDear 

 to be separated, yet a well-chosen series of the numerous 

 Afi'ican species of the class will exhibit a range of transitions 

 so imperceptible, that it will be found very difficult, without 

 careful comparison, to draw a line between one species and 

 the next/'—' The Ibis,' October 1859, pp. 429-432. 



The above are the words of Canon Tristram ; and a more 

 perfect or practical application of the theory of Natural Selec- 

 tion it would be hard to find, even in these days of its fullest 

 acceptance — days when those who formerly strove to over- 

 whelm its author with ridicule and contumely have not 

 scrupled to declare themselves its firmest upholders. 



Yet it is scarcely possible to speak of Darwin's death as a 

 loss. He had done the work there was for him to do. Re- 

 spected by his opponents, honoured by the world of science, 

 loved by his intimates, and venerated by his disciples, his 

 remains lie among those of the greatest Englishmen; and 

 even though, as some may still think, his theory may one day 

 be set aside, as has happened with other well-established 

 theories in times past, the principles on which it is founded 

 will endure for ever. 



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