Family DELPHINIDjE. 
Genus Monodon. 
THE NARWHAL. 
Monodon monoceros, Linnaeus. 
Plate 47. 
The members of this family [Delphinidce) are characterised by usually 
possessing a number of teeth in both jaws. 
As a rule the different species are much smaller than in the Physeteridae, 
though the Killer attains a length of about thirty feet. The blowhole takes 
the form of a crescent, with the points directed forwards. 
The Narwhal or ' Unicorn ' of the whalers, attains a length of from 1 3 to 
16 feet, excluding the tusk, and its widest circumference is 8 to 9 feet, 
according to Scoresby. The tusk or ' horn,' peculiar to the male, tapers to 
a blunt point and has a spiral twist from left to right. It measures from 
5 to 8 feet in length, and has its origin on the lower part of the left hand 
side of the upper jaw. The right hand tusk is usually rudimentary and 
concealed in the jaw. 
In the female the tusk is undeveloped, but both sexes have also some 
rudimentary teeth. 
On rare occasions a pair of tusks are developed in the male. 
Scoresby gives the following description of the species (Arctic Regions, 
vol. i. pp. 487-494) : " The head is about one-seventh of the whole length 
of the animal ; it is small, blunt, round, and of a paraboloidal form. The 
mouth is small and not capable of much extension. The under lip is wedge - 
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