be glanced at are those familiar forms,
the frogs, toads and efts, which, together with their allies, form
another class,--the class _Batrachia_. These animals were long
confounded with reptiles but are really widely distinct from them. They
are arranged in four orders, three of which have living representatives.
The creatures of the first order (the order of tailless Batrachians or
_Anoura_)--frogs and toads--exist over almost all the habitable globe;
and though the number of their kinds is very great, yet they are all
extremely alike in organization. Many kinds (of both frogs and toads)
are found to live in trees, the ends of their fingers and toes being
dilated to enable them to cling to the surfaces of leaves. The most
exceptional species of the whole group are the two tongueless toads, the
_Pipa_ of South America and the _Daclytethra_ of Africa, the last-named
kind being the lowest of all known animals provided with finger nails.

Closely related to the frogs and toads are the efts so common in our
ponds. These familiar English forms are represented in other countries
of the Northern Hemisphere by creatures, some of which (as we shall
hereafter see) are of very great interest indeed. The whole group
constitutes the second Batrachian order--the order _Urodela_.

One of the most noteworthy forms of the order is the eft _Proteus_,
which inhabits the dark, subterranean caverns of Carniola and Istria.
Allied to this is the _Menobranchus_ of North America and the Axolotl of
Mexico. Other forms of the order are the American eft-genera _Spelerpes_
and _Amblystoma_, the _Menopoma_, and the gigantic Salamander
(_Cryptobranchus_) of Japan and China, the eel-like _Amphiuma_--with its
very long body and minute legs--and the two-legged _Siren_ of the United
States.

The third order of Batrachians is one which contains very few species,
but these are very strange, for though allied to frogs they have the
appearance of snakes, or rather perhaps of worms. With long and slender
bodies (marked by many transverse wrinkles), devoid of every rudiment of
limb, they remind us of the before-noticed _Anguis_, _Typhlops_, and
_Uropeltis_ amongst reptiles. The Batrachians in question (which belong
to the genera _Caecilia_ and _Siphonops_) form the order _Ophiomorpha_.

The fourth order of Batrachians is one which has entirely passed away
and become extinct. It is the order _Labyrinthodonta_, and the species
which composed it were, some of