io6 SEALS AND WHALES OF THE BRITLSH SEAS. 



DELPHINID.^. 



The remaining family, Dt'lpliitudcc, as before stated, is a very numerous 

 one. It has ten representatives in the British fauna, contained in seven 

 genera, the first of which, according to the arrangement I have adopted, is 

 that of Monodon. 



THE NARWHAL. 



The Narwhal {Monodon monoccros, Linn.) is a native of the Polar seas 

 seldom leaving the ice ; stragglers have occurred three times on the British 

 coast, one in 1648 in the Firth of Forth, another came ashore alive at Boston, 

 in 1800; the third was taken in Shetland in 1808. 



This species is very numerous in the frozen seas to the north of latitude 

 65°, and is remarkable for the enormous development in the male of the 

 left canine tooth, which is projected forward in the form of a tusk or spear, 

 reaching to the length of six or eight feet, while the right tusk remains 

 abortive, and does not pierce the alveolus. The spear is of fine compact 

 ivory, hollow for the greater part of its length, grooved spirally from left to 

 right, along its outer surface, the spiral generally making five or six turns, but 

 smooth at the end, and bluntly pointed. Although the right canine is rarely 

 developed, a few examples have occurred in which both tusks were present; 

 the female is very rarely furnished with this appendage. 



Mr. J. W. Clarlc, in a paper on a ' Skeleton of Narwhal, with two fully- 

 developed tusks,'* writes as follows: — "The sk'ulls of the Toothed Whales 



Pi'oc. Zoo!, Sol., 1871, pp. 41-53. 



