246 A BOOK OF -WHALES 



et peut-etre donne-t-il aussi de 1'ambre-gris." It 

 seems a belated procedure to attack Lacepede, but he 

 has acquired so big a reputation as an historian of 

 the Cetacea that it is perhaps permissible to quote 

 M. Fischer's remark, that " the scientific element is 

 not conspicuous in his book." 



The Narwhal, genus MONODON, is externally very 

 unlike the last genus, though they possess many 

 structural points in common ; it has but one tooth 

 (rarely two) in maxilla, which has the form of a long 

 tusk ; in female this is rudimentary. 



Vertebrae: C. 7 ; D. n ; L. 6 ; Ca. 26 = 50. Eight 

 ribs, two-headed ; four reach the sternum. Pterygoids 

 as in Delpkinapterus. No dorsal fin. No hairs. 

 Phalanges: I, 2. 11,6. Ill, 5. IV, 3. V, 3 (embryo 



2, 9, 7, 5> 4)- 



This genus is obviously characterised by the 

 singular spirally-twisted "tusk" of the male, which 

 is simply an abnormally enlarged maxillary tooth. 

 Occasionally two teeth are fully developed, one in 

 each jaw ; there is a skeleton in the British Museum 

 which shows this peculiarity. That skeleton has also 

 a small twelfth rib in addition to the normal eleven. 

 Of these ribs the first eight are-double headed ; the 

 same is the case in the Beluga. And, as also in 

 the last - mentioned genus, four sternal ribs exist. 

 Though the Narwhal has no dorsal fin there is a 

 raised ridge along the back an inch in height. 



