168 THE VIVARIUM. 
projection of the ground. A pair of ribs corresponds to each of these 
ventral shields (see Fig. 54). Snakes are not able to move over 
a perfectly smooth surface. Thus it is evident that they move 
FIG, 53.—DIAGRAM SHOWING NATURAL LOCOMOTION OF A SNAKE, after 
Dr. Giinther. 
by dragging their body over the ground, or over some other firm 
base, such as the branch of a tree; hence the conventional repre- 
sentation of the progress of a Snake, in which its undulating body 
~ 
SSS PSS SSIS) 
Fic. 54.—(a) SHOWING THE VENTRAL SCALES OR SCUT OF A SNAKE, (DICE 
SNAKE Coluber tessellatus); (b) SECTION OF a. 
is depicted (Fig. 55) as resting, by a series of lower bends, on the 
ground, whilst the alternate bends are raised above it, is an 
impossible attitude.”? Much of the above statement can easily be 
Fic. 55.—DIAGRAM OF CONVENTIONAL IDEA OF A SNAKE’S LOCOMOTION, 
after Dr. Giinther. 
proved, to a certain extent, by placing a Snake on a large piece 
of well-polished glass. The Reptile is only then able to progress 
by what may be called a series of frantic wriggles. There is no 
purchase on such a smooth surface for the free edges of the scutze. 
