MAMMALIA. 325 



(Myodes) 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 (Hyracotdea). 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 

 a warning. The Syrian Hyrax is supposed to be the shop- 



* 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. In the 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 taquara or bamboo, upon the seeds 

 of which the rats feed. In Ceylon the dying down of StrobilantJus 

 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. 

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