488 ACCOUNT OF THE ARCTIC REGIONS. 



length of the animal from the snout. The tail is 

 from 15 to 20 inches long, and 3 to 4 feet broad. 

 It has no dorsal fin ; but in place of it is an irregu- 

 lar sharpish fatty ridge, two inches in height, ex- 

 tending two and a half feet along the back, nearly 

 mid-way between the snout and the tail. The 

 edge of this ridge is generally rough, and the cu- 

 ticle and rete mucosum being partly wanting upon 

 it, appear to be worn off by rubbing against ice. 



The prevailing colour of the young narwal is 

 blackish-grey on the back, variegated with nume- 

 rous darker spots running into one another, and 

 forming a dusky-black surface, paler and more open 

 spots of grey on a white ground at the sides, dis- 

 appearing altogether about the middle of the belly. 

 In the elder animals, the ground is wholly white or 

 yellowish-white, with dark-grey or blackish spots of 

 different degrees of intensity. These spots are of 

 a roundish or oblong form : on the back, where they 

 seldom exceed two inches in diameter, they are the 

 darkest and the most crowded together, yet with in- 

 tervals of pure white among them. On the sides, 

 the spots are fainter, smaller, and more open. On 

 the belly, they become extremely faint and few, and 

 in considerable surfaces are not to be seen. On the 

 upper part of the neck, just behind the blow-hole, 

 is often a close patch of brownish-black witl.out any 

 white. The external part of the fins is also gene- 

 j-ally black at the alges, but greyish about tlie 



