II SKELETONS OF BIRD AND REPTILE 25 
unites with the sternum, and as the neck vertebrz 
bear small undeveloped ribs this is not an important 
distinction. These neck ribs, short.thin straight bones 
pointing backward, can be seen in fig. 2 (CR, cervical 
ribs) ; the two bases of each are fused with the verte- 
bra, and between them runs a tunnel through which 
the vertebral artery passes. Besides this, the fore 
limb has in some cases, very possibly, moved back- 
ward, since the neck varies very greatly, far more 
than the backbone, in the number of vertebre that 
compose it! Where, then, is our fixed point ? 
I have already described the way in which the neck 
vertebre articulate. The next point to notice is their 
large number, sixteen or seventeen being not un- 
commonly found ; the Ostrich and the Swan having 
considerably more: even small song-birds have not 
less than ten. With mammals seven is the almost 
‘invariable number, the neck of a Giraffe and of a 
Hippopotamus being alike in this. A bird’s neck, 
to be supple and more than snake-like, must clearly 
have a great many vertebre. In the lizard eight is 
the normal number. 
By far the most noticeable feature about the remainder 
of a bird’s vertebral column is its stiffness, due to the 
fact that the vertebrae have become ankylosed together. 
But it is quite erroneous to describe the bird’s back- 
bone as being throughout its length a rigid rod. In 
all the specimens I have examined it bends, at a point 
just in front of the pelvis, with some freedom to either 
1 The question is discussed by Max Fiirbringer in his 
Morphologie und Systematik der Végel, of which there is a good 
summary in Mature, 1888-89. 
