QUEER WAYS OF WALKING. 
Ill 
What we have called a snake’s feet are plates on the 
under side of the body. Those beneath the body proper 
are single, each plate reaching across the entire width of 
the belly, and are called ‘‘belly plates”—gastrosteges, 
if the children want to learn a big word; those beneath 
the tail are in pairs and are called “ tail plates,” or uros- 
teges. These plates are movable, and the hind edge is 
admirably fitted for catching hold of or pressing against 
any object that is firm enough to help the creature drag 
himself along. They may best be observed by holding a 
snake in the hand and letting him slide between the fin¬ 
gers. On a perfectly smooth surface, as a plate of glass, 
a snake is helpless. When a snake would change his posi¬ 
tion, he presses one end of a belly plate—it may be on the 
right or the left side of the body—against some object, as 
a blade of grass, a stick or stone, and begins to push. This 
contracts the joints of the body on one side and relaxes 
them on the other, causing the snake to move in a curve ; 
then he will press a plate against some object on the other 
side, and this will give him a graceful curve in the oppos¬ 
ite direction. As his body advances, he will make these 
curves at his own convenience or in accordance with the 
inequalities of the surface over which he glides. It is a 
graceful mode of motion, but with marked disadvantages, 
one of the most serious of which is the inability to take a 
step backward. No matter what danger he may find himself 
in, he cannot back out. He must either lie perfectly still 
or turn completely upon himself, with great probability 
that he will be observed, caught up and eaten. 
The ability to take a backward step is a very important 
matter, and is closely associated with brain development. 
It implies some capacity to form a judgment, to weigh the 
chances, and to choose between two courses. Hence 
we find it most marked in man’s unrestricted move¬ 
ments in all directions, in the powerful muscles of the 
