AUGUST 173 



colouring; but, no! strange to say their plumage 

 presented an appearance midway between that of an 

 Australian species, T. tadornoides, and a New Zealand 

 species, T. variegata, both of which have much darker 

 and quieter coloration than either of the parents of 

 these hybrids. Upon this Professor Newton observed : 



' The incident possesses an importance hardly to be over- 

 rated by the philosophical naturalist, though it seems not to 

 have met with the attention it deserves. . . . The only ex- 

 planation of this astounding fact seems to be that afforded 

 by the principle of "reversion," as set forth by Mr. Darwin, 

 and illustrated by him from examples of certain breeds of 

 doves, domestic fowls, and ducks, as well as by Mr. Cambridge 

 Phillips in the matter of domestic fowls. It is a perfectly 

 fair hypothesis that the existing animals of New Zealand and 

 Australia retain more of their ancestral character than do 

 those of countries in which we may suppose the struggle for 

 life to have been fiercer and the action of natural selection 

 stronger. . . . The example of reversion (in these sheldrakes) 

 proves that the same effect is produced in species as well as 

 in " races " indicating the essential identity of both, the only 

 real difference being that species are more differentiated than 



The general effect of our cloudy skies and sunless 

 winters upon the plumage of birds mainly resident in 

 the British Isles seems to have been to check the 

 development of bright coloration ; but sheldrakes and 

 kingfishers offer exceptions to this rule, the British 

 sheldrakes displaying more vivid hues and contrast 

 than does any foreign species; while none of the 125 

 known species of kingfisher excels our own species in 



1 Dictionary of Birds, p. 837. 



