40 ON THE CLASSIFICATION OF BIRDS. 
no less than by a variation of structure adapted to s 
habits. 
(42.) But before we proceed further, let us exhibit | 
the divisions just intimated in a more detinite manner, — 
in the following table of the subfamilies : — 
Circles. SYLVIADA, or Warblers. Subfamilies. 
1. Typical. Re eel compressed ; latera] svi ANE. 
2. Sub-typical. Bill and general structure more robust. PHILOMELINE 
Bill depressed at its base; legs length- 
| ened ; strong. 5 {saxrcoua. 
Aberrant 
Claws lengthened, and but slightly cur- 
ved; live upon the ground. { Moraciuine. 
ae rong, panty entire; hinder toe tp rr 
As we shall subsequently touch upon the analogies 
resulting from this arrangement, we may at once pro- 
ceed to notice the several divisions in more detail. 
(43.) The Motacilline, or wagtails, form the most 
aberrant division of this group; they are particularly 
interesting from their various and almost complicated 
relations. They are a small group of purely insectivo= 
rous birds, very well exemplified by the few species so 
common in this and most other countries of Europe. 
They live almost entirely upon the ground, where alone 
they seek their food, which consists entirely of insects : 
damp meadows, and the sides of standing or running 
waters, are the favourite haunts of these birds, and they 
-run with such celerity, that, in this respect, as well as 
in their general black and white plumage, they can only 
be compared to the plovers. We consider them, in 
fact,\as collectively representing the tenuirostral type of 
the perchers, or, what is the same, the grallatorial type 
among birds. The different wagtails of England are of 
the most typical genera (Motacilla and Budytes), These — 
are succeeded by a beautiful little group peculiar to India, 
named Enicurus (fig. 128.), nearly all of which have 
a remarkably forked tail, and are clothed in a plumage 
of pure white, variegated with deep black: next to 
these comes the genus Anthus, or titlarks, slender- 
