Subclass PASSERIFORMES. 
So far as is known, the Passeriformes are the only birds which combine the following 
characters :— 
A. Young born helpless, and requiring to be fed in the nest for many days, but not 
passing through a downy stage. B. A spinal feather-tract on a considerable part 
of the neck, well defined by lateral bare tracts and not split by a spinal bare tract. 
C. A hind toe is always present (generally the first digit, but occasionally, in a 




























few Scansores which have lost the hallux, the fourth digit) and is connected with 
the flexor longus hallucis. 
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The condition of the young at birth, and their subsequent history, is a character of very 
great value in the classification of birds. Of this there can be no doubt whatever. 
However trivial the character may @ priori appear, it is found upon investigation to be one 
of the least variable characters known. 
The modifications in the condition of the young are as follows :— 
Passerine—Young born helpless and nearly naked; not passing through a downy stage 
efore acquiring feathers. 
wAccan me 
Axdeine.—Young born helpless and nearly naked, but passing through a downy stage 
before acquiring feathers. 
Accipitrine— Young born helpless, but covered with down. 
Galline— Young born able to run, and covered with down. 
Megapodiine—Ycoung born able to run, and covered with feathers. 
The taxonomic value of these facts has been unfairly depreciated, in consequence of 
the exaggerated importance attached to some of them by Sundevall. 
B 
