272 ZOOLOGY. 



The genus putorius comprises the common polecat, the 

 ferret, marten, the ermine, and several other species, which 

 all have the head rounded, the fur brilliant and soft, the tail 

 long, and anal glands which secrete a foetid matter. 



The martens differ but little from the polecats, and are 

 equally sought after for their fur. The polecat, which does 

 such damage to the poultry, belongs to this genus. 



The otter (lutra) has the head depressed and the feet pal mated. 

 Otters are aquatic nocturnal animals, inhabiting the margins 

 of rivers and lakes, and subsisting mostly on fishes. 



The genus dog comprises the dog, properly so called, the 

 wolf, and the fox. All these animals are characterized by a 

 peculiar dentition, great strength and agility, senses of hearing 

 and smell acute, claws adapted for digging; they show a 

 partiality (some at least) for putrid flesh as food. Their sight 

 is excellent. 



Fig. 235. The Otter. 



The domestic dog is distinguished from the other species by 

 the curved tail. This animal is born with the eyelids closed, 

 and they open only after ten or twelve days ; the female has six 

 or seven at a birth, and sometimes even^twelve. The dura- 

 tion of life is from twelve to fourteen years ; they have been 

 known, however, to live to twenty, and their age is determined 

 by their teeth, which in the young are white, pointed, 

 and cutting, but in the aged blunted, dark coloured, and 

 irregular. 



The dog is the most complete conquest which man has 

 made in respect of any animal. The entire species has be- 

 come domesticated, so that the primitive condition is lost. 

 The wild dogs found in some countries are merely domestic 

 dogs which, being abandoned, have run wild, and recovered 



