The ulna, which often presents a series of tubercles, indicating
the attachment of the secondary quill-feathers, is usually
a stronger, and a longer, bone than the radius. There are
only two carpal bones, one radial and one ulnar.
|Fig. 85. - The radius (r); ulna (u); radial and ulnar carpal bones (r' u'); with the three digits (i, ii, iii,); of the right for-limb of a Fowl. The terminal phalanges of both the first and the second digits were incomplete in the spicemen figured.
In the Apterygidae
and in the Casuaridae
, there is but one
complete digit in the manus. It appears to answer to the
second of the pentadactyle limb, and is provided with a claw.
In the Struthionidae
, and in all Carinatae
are three digits in the manus, which answer to the pollex and
the second and third digits of the pentadactyle fore-limb; and
the metacarpal bones of these digits are anchylosed together.
As a rule, the metacarpal of the pollex is much shorter than
the other two; that of the second digit is strong and straight,
that of the third is more slender and bowed, so as to leave an
interspace between itself and the second, which is often filled
up by bony matter. The pollex has two phalanges, and the
second of them is, in many birds, pointed, curved, and
enensheathed in a horny claw. The second digit
has three phalanges, and the terminal phalanx
is similarly provided with a claw in sundry
birds. In the ostrich, both the pollex
and the second digit are unguiculate. The
third digit never possesses more than one or
two phalanges, and is always devoid of a
It is a singular circumstance that the
relative proportions of the humerus and the
manus should present the most marked contrast
in two groups of birds, which are alike
remarkable for their powers of flight. These
are the Swifts and Humming-birds, in which
the humerus is short and the manus long; and
the Albatrosses, in which the humerus is long
and the manus relatively short.
In the Penguins, the pollex has no free
phalanges, and its metacarpal bone seems to
be anchylosed with that of the second digit.
The third metacarpal is slender and straight.
The bones of the manus are singularly elongated