IN FEATHERS AND FUR. 69 
against the tree, and go up by means of the same useful ribs and 
scales, the body of the snake being stiff as a stick meanwhile. One 
can't really see how it is done, but done it is, and in just that way, 
too. 
In swimming, snakes will beat the fishes themselves. They 
get on in the water, either by an undulating movement of the 
whole body, up and down, or by the same sort of motion from side 
to side. 
Its way of getting on is not the most wonderful thing about 
the snake. In whatever way you look at him he is a very interest- 
ing object to study. Look first at his bony frame-work. It is 
hardly anything but one long back-bone or vertebrae column. But 
try to turn and twist and wriggle your back around, as the snake 
does his, and you will find you can't do it. The reason he can, is 
that the bones forming that column are provided with the most 
perfect ball and socket joint known. They are like your hip-joint, 
only more perfect, and it would be next to impossible to dislocate 
his back. As to ribs — which he uses for feet, as I told you — he 
is plentifully supplied, some snakes having as many as three hun- 
dred of them. 
No less wonderful are his jaws. Having no hands or feet, of 
course he is obliged to swallow his food whole, and very often it is 
a great deal larger than his mouth and throat. Now, how would 
you suppose he could manage ? That part is provided for in his 
making, and perfectly provided, too. His jaw bones are not fixed 
tightly in one position — as yours are — but are so loosely con- 
structed that they can be widely separated. As the snake draws 
in his food, the mouth gradually grows wider till the bones are 
some distance apart. When once the morsel is down, the ligaments 
contract and draw the bones back to place, and his head begins 
to look natural again. Poisonous snakes kill their prey before 
swallowing, and Boa Constrictors crush them to death ; but those 
which are not poisonous have teeth, all turning backwards, so that 
no creature — however lively — can get away after once he is seized 
by the snake. 
The skin of this interesting creature is very delicate, and 
covers the scales, and as you have no doubt read, it is now and 
then cast off. Perhaps, even you have found old snake skins in the 
woods. When the snake is about to shed his skin, it grows very 
dull in color, and after a while it splits open on the bac^ and fV »e 
