830 PHYLUM CHORDATA : CLASS MAMMALIA 



monkeys there is combination in work, and their communal 

 Hfe seems prophetic of that sociahty which is distinctively 

 human. 



Among Birds, mates are won by beauty of song and 

 plumage ; Mammals are not less characteristically won by 

 force. Rival males fight with one another, and are usually 

 larger and stronger than their mates. The antlers of male 

 deer, the tusk of the male narwhal, the large canine teeth 

 of boars, illustrate secondary sexual characters useful as 

 weapons. But manes and beards, bright colours and 

 odoriferous glands, are often more developed in the males 

 than in the females, and may be of advantage in the rough 

 mammalian courtship. At the breeding season a remark- 

 able organic reaction often affects the animal : the timid 

 hare becomes a fierce combatant, and love is often stronger 

 than hunger. The courtship of Mammals is usually like 

 a storm — violent but passing ; for, after pairing, the males 

 return to their ordinary life and the females become 

 maternal. Some monkeys are faithfully monogamous ; 

 and exceptional pairs, such as beavers and some antelopes, 

 remain constant year after year ; but this is not the way 

 of the majority. 



The duckmole lays eggs and brings up her young in the 

 shelter of the burrow ; the Echidna has a temporary pouch. 

 In Marsupials the time of gestation is very short, and there 

 is rarely a true placental union between the unborn young 

 and the mother. The new-born Marsupials are very help- 

 less, and are in most cases transferred to an external pouch 

 or marsupium, within which they are nurtured. In 

 Eutherian Mammals the gestation usually lasts much 

 longer than in Marsupials — its duration varying to some 

 extent with the rank in the mammalian series ; but there 

 are great diff^erences in the condition of the young at birth. 

 " In those forms," Sir W. H. Flower says, " which habitu- 

 ally live in holes, like many Rodents, the young are always 

 very helpless at birth ; and the same is also true of many 

 of the Carnivora, which are well able to defend their young 

 from attack. In the great order of Ungulates or Hoofed 

 Mammals, where in the majority of cases defence from foes 

 depends upon fleetness of foot, or upon huge corporeal 

 bulk, the young are born in a very highly developed condi- 



