34 
is entirely dependent on the peculiar arrange- 
ments of the back-bone, the ribs and the large 
over-lapping scales that cover the under side of 
the body. The back-bone is arranged on the 
wonderful mechanical principle of the ball-and- 
socket joint, thus allowing a freedom of action 
that explains the snake’s ability to twist and 
turn with lightning swiftness, fearless of injur- 
ious consequences. Just examine this spinal 
column that I removed from a large black snake, 
and you will see the exemplification of the 
wonderful ball-and-socket joint in the con- 
nection of its numerous vertebre., Now this 
same principle exists in the connection of the 
numerous ribs to the spinal column or back- 
bone, and as these ribs are controlled by strong 
muscles you can easily comprehend the snake’s 
swift and graceful motions. You will observe 
from this skin which I removed from a large 
specimen of water snake, that these large scales, 
or scutes as they are called, on the underside of 
the body over-lap; now just feel how rigid this 
lap is. Well, when the snake is in active pro- 
gress over the rough surface of its natural habi- 
tat, it raises these numerous stift over-lapping 
scales against the surface over which it glides, 
and, when you consider their conjunction with 
the numerous ribs, in some spevimens three 
hundred pairs, you can secure a very satis- 
factory understanding of locomotion in snakes. 
The true explanation of locomotion in snakes 
is simply pushing curved portions ot the body 
