MAMMALIA. 325 
(Afyodes) of northern Europe (Fig. 350), famous for their 
migrations,* are allied forms. 
The Lophiomys Imhausi belongs to this family, and is 
one of the most remarkable examples of defensive mimicry 
in the animal kingdom. They inhabit the fissures of the 
rocks in Nubia and Arabia. Allied are the pouched rats, 
hamsters, and the jerboas, or jumping-mice, etc. 
VaLUE.—Three million American muskrat-skins are used as furs 
annually ; also used as felting, and the musk in perfumery. The skins 
of common rats are used as thumbs for kid gloves. 
Order VII. Hoofed Animals (Ungulata). General 
Characteristics —The animals of this comprehensive order 
are the most useful to man, as the camel, horse, pig, etc. 
Some appear to walk upon their toes, which are incased 
in horny hoofs, as the horse, while others are provided 
with blunt, broad nails. 
Hyrax (yracoidea).—These curious animals (Fig. 
351). somewhat resemble the rabbit, and have feet that 
recall the rhinoceros. They have long, curved incisors, 
and feet provided with pads; the toes being incased in 
hoofs, four in front and three behind. They are confined 
to Africa and adjacent countries, and conceal themselves 
in holes and crevices, living in communities. When feed- 
ing, one acts as a sentinel, giving a shrill, prolonged cry as 
awarning. The Syrian Hyrax is supposed to be the shof- 
* These migrations are caused by a naturally restless instinct and 
often by a lack of food. The lemmings on the lower plateau move 
first, and the numbers are gradually swelled, being added to by births 
on the march. They swim rivers, and in coming to the sea are lost in 
it, thinking it a river. Inthe Brazilian province of Parana a rat-plague, 
that devastates the country, occurs about every thirty years, and is simul- 
taneous with the dying out of the ¢¢guara or bamboo, upon the seeds 
of which the rats feed. In Ceylon the dying down of Strobilanthes 
every seven years causes a similar plague, and in Chili the rat-swarms 
are coincident with the destruction of a species of bamboo (colligue) 
every fifteen or twenty years, 
