SNAKES. 179 
uninitiated onlooker will feel inclined to give, is that it is some- 
thing belonging to the victim. But, no doubt, on second thought 
this explanation will appear unsuitable if the prey is observed 
to be dead (as it would be, most likely, if in the jaws of a con- 
stricting or poisonous Snake), and this strange thing is noticed to 
be endowed with life. Then perhaps it will be supposed that the 
Snake in making the exertion which is necessary to swallow so 
large a mouthful, has injured itself. 
The fact is, that this curious-looking substance does belong to 
the Snake, and the Reptile is not hurt. It is, indeed, the upper 
part of the windpipe, which has been brought forward by means 
of certain muscles provided for the purpose; and that which was 
observed to be opening and closing was the glottis, which is 
situated at the top of the windpipe. As this glottis can be 
brought forward beyond the limits of the jaws during the time 
the Snake is swallowing an unusually large mouthful, it will be 
plainly understood why the Reptile is not choked under such cir- 
cumstances. While a large Python is performing a difficult act 
of deglutition, as much as an inch, or even more, of the upper part 
of the windpipe may be seen. 
When a Snake’s mouth is opened two tubes can be observed to 
be situated between the two lower jaws—the bottom one is the 
sheath of the tongue; and the top one, which is placed a little 
farther back, but above and parallel to the tongue-sheath, is the 
larynx or upper part of the wind-pipe. The glottis, under these 
circumstances, will probably be seen at work. 
Reference has already been made to what is frequently called 
the “‘ Snake’s change of skin.” This, however, is not a correct 
expression. The Reptile does not change its skin, but its epi- 
dermis, or cuticle. This is a thin membrane which covers the 
true skin. We have this possession, of course, in common with 
animals, and our attention is sometimes painfully drawn to it 
when we have blistered our hands through some unusual manual 
exercise, or our feet by ill-fitting boots. This epidermis is also 
known as scarf-skin. When a reptile, especially a Snake, casts 
its old epidermis that its place may be taken by new, it is said 
to slough. And that which is thrown off is called the slough, or 
cast, or exuvize (there is no singular). 
N 2 
