228 REPTILES

and everywhere inspire the same terror among the
natives.

The harmless snakes include the great anaconda,
which is thirty feet long—the largest of the boas,
larger even than Boa constrictor, The boas are all
South American; in the Old World they are repre-
sented by the pythons, or rock-snakes; several
genera of the Pythonide being Australian. The
pythons can swim as well as climb, and some of them
are four-and-twenty feet long. They none of them
poison their prey ; they kill it by coiling round it and
squeezing it. Among the other colubrine snakes are
our own smooth snake and grass snake.

LACERTILIA.—The lizards have been described
as tailed reptiles having legs; but the legs and the
tail are not to be trusted to, for in some cases a lizard
will jerk off his tail and eat it for want of a meal, and
find no difficulty in growing another ; and if he loses
a leg he can in time replace it. The legs of the
lizards are of every degree: there are lizards with
five claws, lizards with four claws, lizards with three
claws, lizards with two claws, lizards with one claw,
lizards even with no claws or legs at all. There are
over 1,500 lizards altogether—the lizards of the
land, of the trees, of the water, even of the sea.
One lizard only, the Mexican Heloderma horridum,
is poisonous, and has fang-like teeth, The mouth
of a snake is expansible, that of a lizard is not;
and while the snakes have no breastbone, and never
more than a trace of a pelvis, the lizards generally
have both girdles, shoulder and hip, more or less