90 THE COURTSHIP OF ANIMALS 



(Mesoplodon) ; the second the Narwhal. The former is the 

 only vertebrate which in a wild state wears a muzzle ! 

 In this species the teeth have totally vanished save for a 

 pair in the lower jaw, which are found towards the end 

 of the jaw. These in the adult, or perhaps we should say 

 senile, male grow upwards and inwards, finally meeting 

 one another above the upper jaw, so as to make it im- 

 possible for the animal to open its mouth more than the 

 fraction of an inch ! Surely here we have a secondary 

 sexual character carried to an excess, and so proving not 

 only disadvantageous to the animal, but positively 

 disastrous, for it seems clear that so hampered the creature 

 can feed only on the most minute forms of animal life, 

 which could only be captured and swallowed with difficulty. 

 It is true that the Rorquals feed on excessively minute 

 Crustacea, but they are able to take in enormous quantities 

 at a time, the " whalebone " serving the office of a sieve 

 to prevent their escape. The Mesoplodon has no such 

 aids. One is tempted to believe that the skulls displaying 

 this most curious feature are abnormal, comparable to 

 those, say, of rabbits wherein the teeth have grown so 

 excessively long as to close the mouth, on account of the 

 displacement of the cutting surfaces by accident. But 

 there is nothing to afford support to this view, and one 

 must therefore fall back on the suggestion of senility. 



The Narwhal has long been celebrated for the enormous 

 size of the canine teeth, the only teeth present in the jaws. 

 As a rule, only one leaves its bony socket, the other, 

 commonly the right, remaining as a mere vestige, seven 

 or eight inches long within the skull. The protruding 

 tooth, which is spirally fluted, may attain a length of nine 

 feet. Occasionally both teeth are developed, and in this 

 case the spiral is the same, differing in a very striking 



