Mole-rats_ are a sort of combination between moles and rats: hence
their common name. One species is found in Eastern Russia; where it
burrows much after the fashion of the mole--living principally upon
roots. Two other kinds belong to South Africa. Both these are of large
size, nearly as big as rabbits. On the plains, they make extensive
excavations, which often prove dangerous to the horse and his rider--
causing the former to stumble. The Dutch of the Cape know them by the
name of Sand Moles.

The _Hamsters_ differ considerably from the marmots in their mode of
burrowing. They make their underground dwellings very extensive--having
a great many chambers and galleries. In these they collect vast stores
of food--consisting of grain, peas, and seeds of various kinds.
Sometimes two or three bushels of provision will be found in the
storehouse of a single family. The hamsters do not confine themselves
exclusively to a vegetable diet: since it is known that they will kill
and eat birds, or even small quadrupeds. In this respect they resemble
the common rats; and, therefore, it is idle to talk of mere
_herbivorous_ genera of animals. The hamsters are very fierce little
creatures: constantly fighting with other quadrupeds, and even among
themselves; but the polecat is their master and tyrant, and carries on a
war of extermination against them--following them through the intricate
ways of their burrows, and destroying them even in their dens!

There are several species of hamsters in Europe and Asia, and also in
North America: for the animal known as the Canada Pouched Rat is of this
kind, and so also is the Tucan of Mexico. So also is that very singular
and beautiful creature, the Chinchilla of South America--so celebrated
for its soft and valuable fur.

The _Lemmings_ are another form of small rodent animals, celebrated for
their extraordinary migratory habit; which resembles that of the grey
squirrels of North America. There are several species of lemmings
belonging to the northern section of the Old Continent--in Eastern
Russia and Asia. One or two are found in North America--in that part of
it known as the Hudson's Bay Territory.

The _Spinous Rats_ are little animals much resembling ordinary rats; but
with the peculiarity of having stiff spines growing among their hair,
after the manner of porcupine quills. There are several species of
them: all natives of tropical America.

The _Jerboas_ are, perhaps