XV CLASSIFICATION 385 
The few species, the Ratite, which we have 
separated off from the rest, are held to have in 
them less of what constitutes a bird than any other, 
We will now go to the other end of the scale, the 
most highly specialized of the Carinate. These are 
the Passeriformes or sparrowlike birds, the largest 
order of all. Of the 367 birds which Mr. Howard 
Saunders counts as British, 125 belong to this order. 
This leaves 242 for the other sixteen. The Passeri- 
formes may be known by these marks: (1) Their 
hallux or first toe is always turned backwards and 
is furnished with a larger claw than any of the 
other three ; (2) there is no connection between the 
branched tendon and that which bends the hallux ; 
(3) there is no ambiens; it is very curious that this 
muscle, whose duty is to help the toes to grip, 
should be absent in these perchers; (4) there is a 
well marked feather tract on the neck ; (5) the young 
are born helpless, and hardly ever pass through a 
down-stage; (6) the oil gland is present and is 
naked; (7) they are without exception perchers. 
This last point is not, of course, a structural char- 
acter, and is introduced only as supporting the 
others. To this order belong most of the very 
commonest of our birds; among them are none of 
much size except the Magpie, the Raven, the Crow, 
and the Rook. The Swallow is a Passerine, whereas 
the Swift belongs to a quite different order, what Mr. 
Mivart calls the Coraciiformes or crowlike birds. In 
this order the young are born with a little down upon 
them, the toes are united for some distance, and 
the first toe has not a larger claw than the others. 
CG 
