iS6 



THE GNAWERS OR RODENTS. 



ships, and settled everywhere — in the Tropics 

 as in the Frigid Zone, in America as in 

 Australia. But this almost universal do- 

 minion has been greatly encroached on by 

 the immigration of another rat, more powerful 

 and more ferocious, from Asia into Europe, 

 and in the latter continent the Brown Rat, as 

 it is called [Mus decumanus), fig. 211, has 

 everywhere displaced 

 the black rat. In the 

 year 1727 prodigious 

 swarms of the brown 

 rat swam across the 

 Volga in the neigh- 

 bourhood of Astra- 

 khan, and since then 

 this species has multi- 

 plied with great rap- 

 idity, extinguished the 

 black rat, peopled 

 Europe, and has also 

 reached transoceanic 

 countries on ships. 

 At the present day the 

 brown rat has already 

 advanced beyond the 

 Mississippi, and soon 

 it will bave overrun 

 the whole territory of 

 the United States as 

 it has already done 

 the whole area of Europe. It lives in the 

 sewers of towns, in houses, barns, and stables, 

 and may become a real plague, and above 

 all on ships. The brown rat attains a length 

 of 8 inches; the tail has only about 220 rings. 

 The hair is coarse, and of a grayish-brown 

 colour on the back, lighter underneath. It 

 eats anything, destroys everything, burrows 

 everywhere, is courageous and fierce, and, 

 like all members of the group, extraordinarily 

 prolific. An albino variety with white hair 

 and red eyes is pretty common. 



The Mice are not such mischievous de- 

 stroyers, but nevertheless are far from agree- 

 able companions. In fig. 212 is represented 





the Common Domestic Mouse [Mus musculus), 

 which attains a length of 4 inches at the 

 most. Its tail, with about 180 rings, is just 

 about as long as the ; body. The colour is a 

 well-known gray, a little darker on the back 

 than on the under parts. The houses, cellars, 

 and barns which it inhabits it is very un- 

 willing to quit, and it hardly ever ventures 



beyond the gardens 

 into the fields, where 

 it is replaced by the 

 Field-mouse [Mus ag- 

 rarius); in the woods 

 the Long-tailed Field- 

 mouse takes its place 

 [Mus sylvaficus); and 

 in many corn-fields 

 and reedy marshes 

 there is a smaller 

 species, the Harvest- 

 mouse [Mus (Micro- 

 mys) minutus), which 

 builds for itself a 

 round nest hanging 

 to the stalks of the 

 corn or reeds. In Al- 

 geria and the steppes 

 ^pf the interior of 

 frica occurs one of 

 e prettiest members 

 this genus, the 



. 212. — The Common Domestic Mouse (Mus musculus) 



Of 



Striped or Barbary Mouse [Mus striatus {bar- 

 barus)), fig. 213. Its fawn-coloured fur is 

 marked with ten dark -brown longitudinal 

 stripes; the belly is white. It attains a length 

 of very nearly 5 inches. 



All these mice lead much the same kind 

 of life, residing in holes, where they make 

 nests for their frequent litters of young. 

 From eight to ten young ones are always 

 born at a birth. The period of gestation is 

 never more than four weeks, and at the age 

 of four months the young animals are already 

 capable of reproduction. A new period of 

 gestation begins almost immediately after the 

 birth of a litter. If one will only take the 



