THE BODY. 
7 
length of its vertebrae, which are apportioned by a certain 
fixed number; but with birds the number of vertebrae 
increases in proportion to the length of the neck. Hence 
they may vary in number from nine up to as many as 
twenty-four. The number of the remaining vertebrae is 
very uncertain. The dorsal vertebrae number from six to 
ten, seldom more than a quarter of the whole. The sacral 
vertebrae (in many cases almost completely united) are 
always more in number, reaching from twelve to twenty. 
The caudal vertebrae are exceedingly supple, and number 
from five to nine. Of these the last or hindmost is 
more or less perfectly developed in proportion to the 
resistance which the tail has to overcome, or to the 
development of the feathers in the same. In the frame¬ 
work of the shoulder the merrythought, or furculum, is 
noteworthy. It is firmly connected with the humerus 
and caracoid, and is composed of the two clavicles 
blended into a single bone, but is not always affixed to 
the sternum. The wing consists of an upper arm-bone, 
which is very strong and hollow, and two lower arm-bones 
of nearly equal length; the wrist, or carpus, is composed 
of one or two bones, and the palm, or metacarpus, of two 
or three. Attached to these are one, two or three fingers, 
which are, however, enclosed together under one common 
skin. 
The pelvis (except in the Ostrich) is open beneath. 
The leg is composed of the femur, tibia, and fibula, the 
knee-pan, or patella, the tarso, metatarsus, and the 
phalanges, or bones of the toes ; the latter number from 
two to four, of which two invariably, and in most cases 
three, though very rarely all four, are turned to the front. 
Sometimes one toe is so jointed that it can turn either 
backwards or forwards. The bones of the skull unite 
