THE SPECIFIC CHARACTERS OF BIRDS. 527 
racter, being founded merely upon a comparison of parts, 
in themselves of little interest, in as far as regards mere 
length ; nor does it appear in what respect advantage is to 
be gained from knowing that the middle toe of one duck 
is a quarter of an inch longer than its tarsus, or a tenth 
shorter than that of another duck. No systematic ornitho- 
logist has as yet thought of founding his generic characters 
upon the length alone of the beak ; and, although the case 
be somewhat different with regard to the feet, they seem 
to be as little capable of affording distinctive marks for the 
species. 
The jfb?^m of the wings, as well as of the tail, has been 
used as a character ; and here all the requisite qualifications 
are present : but in these parts there is by no means a suf- 
ficient variety of form to admit of any thing like general 
application ; and, in very many cases, almost all the species 
of a genus have precisely the same form of wings and of 
tail. Witness the genera, Gallus, Phasiatius, Sterna, Larus, 
Motacilla, Phaeton, Turdus, Oriolus, &c. In fact, from 
this uniformity of the wing in birds of the same genus, 
Temminck has derived one of his numerous generic cha- 
racters. 
The presence of certain appendages (or ornaments, as 
we usually denominate them, forgetting that Nature pro- 
duces nothing merely ornamental), such as tufts of feathers 
on the head or neck, of various forms, — fleshy, cartilaginous 
or bony excrescences on the same parts, — spurs on the 
legs, — and spines at the flexures of the wings, has also been 
used to characterise specific forms, as in the Pavo cristatus^ 
the different species of the genus Craop^ Phasianus cornutus. 
Ph. nycthemerus^ Anas gambensls^ Palamedea cormita^ he. 
All these are only occasionally present, however, with the 
exception of the spur on the flexure of the wing which is 
nearly universal, and consequently can only furnish an oc- 
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