NUTHATCH. 525 



Yokohama, to which the name of S'ltta amurensis has been given, scarcely 

 differ from examples from the Baltic provinces : the colour of the lov^er 

 breast and belly is pale chestnut ; that of the throat and upper breast is a 

 purer white ; aad the chestnut on the flanks is scarcely so much developed. 

 This species is said to range as far south as North China; but in 

 Central China and East Thibet a form occurs, to which the name of 

 Sitta sinensis has been given, which only difl^ers from South-European 

 birds in being slightly smaller, the length of wing measuring from 3'0 to 

 2-9 inch. 



All these various forms of the Nuthatch can only be considered local 

 varieties of one species, being in most cases certainly, and in the others 

 probably, connected together by intermediate forms. In comparing these 

 forms one with another it is important to bear in mind the fact that the 

 females are slightly less than the males, and generally have the pale chest- 

 nut on the breast and belly more strongly developed than in the male, and 

 the rich chestnut on the flanks and under tail-coverts slightly less so. In 

 the tropical species with dark legs, which are most nearly allied to our 

 Nuthatch, the underparts are of a still richer and deeper chestnut, e.Kcept 

 S. nagaensis, which was obtained by Col. Godwin-Austen in Assam. It is 

 somewhat remarkable that no Nuthatch belonging to this group has been 

 found in Eastern Persia or in Turkestan. 



To the casual observer the Nuthatch is a small Woodpecker, as the 

 Swift is mistaken for a large Swallow. In both cases the superficial 

 resemblance is very striking. The habits are the same ; and if the foot 

 differs, there is little or no diEFerence in the form of the bill. Modern 

 biologists tell us that these external characters are of little value in classi- 

 fication, that internal characters alone are reliable, and that the Nuthatch 

 is more nearly related to the Swallow than to the Woodpecker, and that to 

 find the common ancestors of the Woodpeckers and the Swifts the geolo- 

 gical record (the genealogical tree) need not be searched so far back as 

 would be necessary to discover the common ancestors of the Swifts and 

 the Swallows. It cannot be denied that, in the struggle for existence, 

 birds have been obliged to change their habits to accommodate themselves 

 to the changes of climate which have taken place in the district where 

 they have resided. The Rock-Nuthatch, so common in Greece and Asia 

 Minor bears so close a resemblance to our bird, that it is difficult at first 

 to believe that its habits are so different. No character is so variable as 

 the form of the bill, which seems to have the power of adapting itself with 

 astonishing rapidity to the nature of the food with which it has to deal; 

 and it is somewhat surprising that it should still be considered of so 

 much generic importance by some writers. At the same time it must be 

 admitted that no one can compare the results of different dissectors 

 without coming to the conclusion that, even in what are supposed to be 



