THE DOLPHINS. 



II 



white, mottled with numerous brown spots. 

 The animal attains at most a length of 20 

 feet, frequents the same parts of the Arctic 

 Seas as form the home of the beluga, and 

 feeds on cephalopods, holothurians, and fishes. 

 The mouth is very small. 



What distinguishes the narwhal from all 

 other cetaceans is its peculiar dentition. It 



has no teeth in the lower jaw, and in the 

 upper jaw only two straight canines are 

 formed in deep sockets of the maxillce. In 

 the female these teeth remain through life 

 in the sockets, so that it seems to be tooth- 

 less, but in the male one of these canines 

 grows straight out to an extraordinary length. 

 There have indeed been found rare examples 



1' ig. 139. —The Narwhal (Monodon monoceros). 



of narwhals with two tusks, but in this case 

 they were always unequally developed, and 

 usually it is the left canine which grows out 

 in this manner, while the right remains 

 embedded in its socket. In consequence of 

 this peculiar dentition the want of symmetry 

 which characterizes the skull of cetaceans 

 generally reaches its acme in the narwhal. 

 In the embryos two small incisors and an 

 upper molar are also to be seen, but these 

 are soon lost. 



The socket of the canine which forms 

 the tusk is so wide that the premaxilla (the 

 bone which holds the upper incisors when 

 present) comes to form part of its wall. The 

 tusk is straight, and composed so to speak 



of spirally twisted strands, and may attain 

 a length of 10 feet. On these tusks, for 

 which high prices were formerly paid, has 

 been founded the fable of the unicorn, which 

 still figures in the English national coat of 

 arms. 



Manifestly the tusk of the narwhal is a for- 

 midable weapon, but it is apparently used only 

 in battles between males, and not as a means 

 of defence against enemies or for other pur- 

 poses. Broken or injured teeth are often met 

 with, but the narwhal has never been seen to 

 use its tusk against the killer-whale, which 

 commits fearful ravages among them. All 

 observers are agreed in depicting the nar- 

 whals as peaceable creatures and excellent 



