2 THE ORDER OF SNAKES—OPHIDTIA. 
Snakes are naked, that is, they are not supplied with any external 
covering such as hair or feathers. Their epidermis is laid in scale-like 
folds on the back and sides, and forms plates on the belly, and generally 
broad though not imbricate plates on the crown (except in the genus 
Yorelia—the Diamond and Carpet Snakes—which have the head covered 
with numerous irregular small scale-like plates). The epidermis is shed, 
at regular intervals, several times a year, and removed in one piece, 
including the part over the eyes, which, being without lids, may be 
easily traced in the cast-off skin. At some period before the epidermis is 
shed, the snake retires to a quiet, and, if possible, damp place, where the 
skin soon loses the usual gloss and becomes opaque, whilst the eyes grow 
blind, as the new skin is formed beneath the used-up epidermis. When 
ready, the reptile selects a forked branch, or the cleft of a rock, and, 
pressing through, emerges from the old covering, which is left complete, 
and turned inside out behind. The shedding of the skin in a perfect 
state is a sign of good health ; but when removed in shreds, the snake is 
suffering from some malady. Shortly after this metamorphosis serpents 
become very sensitive, and more inclined to bite, when disturbed, than at 
other times. 
The teeth are hook-like, curved backwards, very sharp, and designed 
for retaining, not crushing or masticating, the prey; with few exceptions, 
the palate is furnished with teeth also. 
All the yiscera are of a peculiar elongate form, there is but one 
lung developed, and the organs of generation are double. Some serpents 
bring forth their young alive, others lay eggs, but in many cases these 
eggs when deposited contain already well-developed young. Only one 
family—the Pythons—incubate their eggs. 
The division between Snakes and Lizards is not clearly defined, and 
one group merges into the other by scarcely perceptible degrees. The 
first family of Blind Snakes presents many characters which remind us 
of the lizard type; such as the large, polished, adherent, and rounded 
scales, the narrow mouth, and the frequent absence of the gular furrow 
peculiar to almost all Ophidians. 
Some authors have classed the Blind Snakes with the Lizards, but 
they differ from them in the loose connection of their jaw-bones—a 
character which, according to Gimther, must be considered as peculiar to 
