17S ON THE CLASSIFICATION OP BIRDS. 
(153.) In regard to solitary builders^ we’find all the 
purely insectivorous genera are of this class. Among 
the shrikes, thrushes, warblers, titmice, and fly-catchers, 
there is not an instance of one species either living or 
building in societies. The same may be said of car- 
nivorous quadrupeds, which, with the single exception 
of the genus Cams*, piusue their sanguinary habits 
alone, or accompanied only by their mates. In pro- 
portion to the development of the social principle is 
the disposition, not only to live, but to breed in so- 
cieties ; but neither one or the other is manifested in 
the birds we have just mentioned, at least to any extent. 
Fieldfares, it is true, are seen congregated into loose 
flocks towards autumn, and the long-tailed titmice 
form small parties, probably family ones, at the same 
season, but neither are known to build together. 
(154.) To describe the construction of an ordinary nest 
would be superfluous ; the coarsest materials are always 
used in the first instance, as if to form the basis of the 
whole, and as the building proceeds, finer materials are 
selected ; last of aU comes the lining, which is generally 
composed of hairs, or some other elastic substance, to pre- 
serve the form of the concavity, and with feathers to 
create additional warmth : for an arboreal nest of this 
description a firm support is necessary ; hence it is gene- 
rally placed between the forked branches of a tree : this 
answers many purposes ; the nest is not liable to be 
shaken by the wind, its base is firm, and being, as it 
were, in the centre of the foliage, it is more effectually 
screened from observation. Numerous instances of this 
sort of nest occur among our insectivorous and graniv- 
orous small birds ; the most delicate of these are made 
by die chaffinch and the goldfinch. Variations from 
the structure and situation of these are seen in the nests 
of sparrows and fly-catchers, where the materials are 
coarser, and the fabric placed on the side of a building. 
The hedge accentor, again, builds near the ground, and 
* 1'his pompreliends the wolves, dogs, foxes, and hya?na-dog8. See 
Classification of Quadrupeds. 
