xv CLASSIFICATION 385 



The few species, the Ratita^, 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 Carinatae. 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. 



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