A History 
of Birds. 
(7 2) 
THE BIRD WORLD. 
A History of Birds. 
By W. P. PYCRAFT, A.L.S., F.Z.S., Etc. 
{Continued from fi. 44.) 
CHAPTER I. 
Birds, then, in the possession of feathers, are 
unique in the scheme of nature; so that by this 
character alone we may distinguish them from 
all the remainng back-boned animals, while there 
can be no sort of doubt but that they owe their 
descent from some reptilian ancestor. 
Let us now pass on to consider one or two 
other peculiarities of birds; peculiarities which 
have gone on developing and perfecting since the 
time of splitting off from the reptile stock. 
The Story of the Wing. 
Surely the most important of these is to be 
found in the fore-limb. This we know as the 
“wing.” Even stripped of its feathers, we could 
trace the wing of the bird from the fore-leg of 
any other animal. Yet ,it cannot be used as an 
absolutely distinctive character, since in some 
of the Ostrich tribe, for example, it has become 
degenerate, and so reduced in size as to be hardly 
recognised; while if we take fossil forms into 
consideration, we shall find that it becomes still 
more dwarfed, until, as in the Moas, it is lost 
altogether. 
The principal features in which it differs from 
the fore-limb of other animals are to be found in 
the bones of the wrist and hand. In the wrist 
only two separate bones can be found, though in 
the embryo the rudiments of several can be made 
out; these disappear, however, before hatching 
takes place. The bones of the hand and fingers 
are reduced to three in number—the thumb and 
Photo copyright by] [ IV. S. Berridge , P.Z.S, 
The Frigate-bird at the Zoo. 
The Frigate.bird shows the wing at its extreme develop¬ 
ment in point of size, this bird spending most of its time 
in the air. 
first and second fingers. The first portion of 
these finger-bones—which answer to the bones 
that, extending between the wrist and the" bases 
of the fingers, make up the palms of our hands— 
are firmly welded together, the base of the thumb 
being hardly traceable. The second and' third 
are welded together at each end, enclosing a 
space, while the finger joints are represented, 
in the second finger by two, or sometimes three 
bones, and the third by one bone only. 
This very remarkable wrist and hand have 
reached this unique stage of development as a 
response to the peculiar needs of the bird’s flight, 
the hand being drawn out into a long rod, across 
which the bases of the quill-feathers are securely 
lashed by ligaments. 
Process of Transformation. 
The wing, no less than the rest of the skele¬ 
ton, furnishes convincing evidence to show that 
the bird, as we see it to-day, has acquired this 
form by a slow process of transformation. In 
many birds, as in the Duck, the Water-hen, or 
any of the Hawks, there will be found on the 
thumb and the tip of the second finger, a small 
claw—the last remaining vestige of a claw that 
was once useful. In some other birds, as in the 
barn-door fowl, for example, similar claws will 
be found only in the embryo—i.e., the developing 
chick before it leaves the egg—though quite 
commonly the thumb-claws persist throughout 
life. Examine the wing of the next fowl you 
come across, and likely enough you will find it. 
Now if we go back to the Archaeopteryx, we shall 
find that the wing possessed a large claw on 
each of its three fingers. And more than this ; 
in this ancient bird we find that the second row 
of wrist bones—those at the base of the fingers— 
though welded together to form a half-moon-, 
shaped bone, yet remained distinct from the 
fingers. They, in fact, retained throughout life 
the condition which is met with to-day only in 
very young birds. When a yet more ancient 
bird than the Archaeopteryx is discovered, it is 
safe to predict that a yet more complete series 
of wrist bones will be found. We shall, in fact, 
have all the links from the reptile to the present 
day bird. 
High Temperature of Birds. 
In one particular the bird and the reptile are 
very different, inasmuch as while the reptiles are 
“ cold-blooded,” the birds are hot-blooded crea¬ 
tures ; indeed, in this matter they outdo the mam¬ 
malia, the temperature ranging from 100 deg. 
to 112 deg. The highest figure is attained by 
