XII THE BELUGA AND NARWHAL 273, 
The Beluga is a northern species purely. The reputed form, 
D.- kingii, was said to come from Australian seas; but there 
seems to have been an error in this statement. It is interesting 
to note that the white colour, so characteristic of the genus 
eradually pale as they advance towards maturity. Delphin- 
apterus leucas reaches a length of 10 feet, and like other 
Porpoises will ascend rivers in search of food. It is said to 
be specially addicted to salmon. Among the contents of the 
stomach have been found quantities of sand. But this habit of 
swallowing sand or pebbles has been noted in other Whales. 
Whether it is or is not accidental (taken in with ground-living 
food), it seems hardly likely that it is used for purposes of 
ballast! /The Beluga has a voice; but the name “Sea Canary ” 
is hardly suitable to it. A specimen of this species, recently 
described from the shores of Scotland Gt is often thrown up 
upon our coasts), which had got entangled in the stakes of a new 
net, was regarded by the natives, on account of its white colour, 
as a ghost.. Externally, besides its colour, the Beluga is remark- 
able for possessing a distinct neck, which is correlated of course 
with the freedom of the cervical vertebrae, and is also seen in 
Platanistidae. 
The Narwhal (J/onodon) is closely allied in structure to the 
last genus. It has the following anatomical characters :—The 
teeth are reduced to a single “horn” in the upper jaw, which 
is rudimentary in the female. The neck vertebrae are free. The 
vertebral formula is C 7, D 11, L 6, Ca 26. The pterygoids 
are as in Delphinapterus, and, as in that genus, there are no hairs 
upon the face or dorsal fin. 
This genus is of course most obviously characterised by the 
twisted tusk of the male, which is occasionally double. This 
tusk has given to the only species of the genus, M. monoceros, 
both its generic and specific name. The animal has a spotted 
colour; but, as in the case of the Beluga, old animals tend to 
become white. The use of its horn to Monodon has been 
debated. In the first place it is clearly a secondary sexual 
character. The males have been observed to cross their horns 
like rapiers in a fencing match. It may be that they are used in 
more serious combats. An ingenious suggestion is that the long 
and strong tusk enables its possessor to break the thick ice and 
