7 6 Journal of Travel and Natural History 



build the first-class carriages so as to imitate a number of coach-bodies 

 joined together; and the arm-loops for each passenger to hold on 

 by, which were useful when bad roads made every journey a succes- 

 sion of jolts and lurches, were continued on our smooth macadam- 

 ised mail-routes, and, still more absurdly, remain to this day in our 

 railway carriages, the relic of a kind of locomotion we can now 

 hardly realize. With these and a hundred similar facts everywhere 

 around us, we may fairly impute much of what we cannot under- 

 stand in the details of Bird-Architecture to an analogous cause. 

 If we do not do so, we must assume either that birds are guided in 

 every action by pure reason to a far greater extent than men are, 

 or that an infallible instinct leads them to the same result by a 

 different road. So many and such well-known facts are opposed 

 to both these views, that I do not think it necessary here formally 

 to refute them. 



The preceding observations are intended to shew that the exact 

 mode of nidification of each species of bird is probably the result 

 of a variety of causes, which have been continually inducing 

 modification in accordance with changed organic or physical condi- 

 tions. The most important of these causes seem to be, in the first 

 place, the structure of the species, and, in the second, its environ- 

 ment. If, therefore, we find less important and more easily 

 modified characters than these correlated with peculiarities of 

 nidification, we shall be justified in concluding that the former are 

 dependent on the latter, and not vice versa. Such a correlation I 

 am now about to point out. 



Considering the main purpose of bird's nests to be the protec- 

 tion of the eggs and the security and comfort of the young birds, 

 we may group them under two primary divisions, according as they 

 more or less completely fulfil this important function. In the first, 

 we place all those in which the eggs and young are hidden from 

 sight, no matter whether this is effected by an elaborate covered 

 structure, or by depositing the eggs in some hollow tree or burrow 

 underground. In the second, we group all in which the eggs and 

 young and sitting bird are exposed to view, no matter whether 

 there is the most beautifully formed nest, or none at all. King- 

 fishers, which build almost invariably in holes in banks ; wood- 

 peckers and parrots, which build in hollow trees ; the Icterida; of 

 America, which all make beautiful covered and suspended nests, and 

 our own wren, which builds a domed nest, are examples of the former; 

 while our thrushes, warblers, and finches, as well as the crow- 



