ing from the orders of crocodiles and lizards to that of
serpents--_i.e._, to the order _Ophidia_--we might select as first to be
mentioned kinds which much resemble the legless lizards; but such kinds
are not familiar ones in Europe.

The only serpents met with in England are but of three species--two
harmless snakes and the common viper, which latter is the only really
poisonous reptile in this country.

Of the harmless snakes, the ringed or collared snake (_Tropidonotus_) is
much the commoner and more widely diffused. It ought to escape
destruction on account of the ease with which it may be discriminated
from the viper by means of the white collar-like mark which appears so
conspicuously just behind its head.

Our viper is the type of a large and poisonous family, but by no means
all poisonous snakes are vipers. The deadly cobras belong to a different
group, having much more affinity with our own harmless snakes than with
the vipers. The rattle-snakes again form a family (_Crotalidae_) by
themselves.

There are such things as true sea-serpents, and they are poisonous. They
are not, however, allies of any "sea serpent," such as every now and
again figures in startling paragraphs in our journals. The true
sea-serpents are snakes of small or moderate size, which have their
tails flattened from side to side, and which inhabit the Indian Ocean.
Of other serpents which are not poisonous, the family of boas and
pythons (which kill by crushing) is tolerably familiar to all who have
visited zoological collections. There are many beautiful and harmless
snakes, such as the families of tree-snakes and whip-snakes, but the
snakes which more or less resemble legless lizards are burrowing forms
which have the habits and more or less the appearance of earth-worms,
such as those which form the families of _Uropeltidae_ and _Typhlopsidae_.

The last existing reptilian order (_Chelonia_) includes, besides the
land tortoises of very various dimensions, a variety of aquatic forms.

The best known of these in this country, is the marine family
(_Chelonidae_), to which the edible and tortoise-shell turtles belong.
The best known family in the United States and in the Continent of
Europe, is the _Emydae_, to which pertain the terrapins or ordinary river
tortoises. Besides these, however, there is a very small family
(_Trionicidae_) of curious and exceptional forms, called mud-tortoises
(_Trionyx_).

The creatures which have next to