Marvels of the Universe 687 
Naturally one asks of what use is this remarkable tooth ; is it a 
weapon, or is it merely ornamental ? So far it is impossible to 
answer this question with anything like certainty, as is shown, 
indeed, by the several attempts which have been made to explain 
its use. According to some authorities it is employed to break 
open breathing-holes in the ice, for it is a dweller in the Arctic 
Seas. But since the female is tuskless this explanation does 
not find much favour. Others say it is used by the males in 
fighting for females, as stags use their antlers; and males have 
actually been seen crossing their weapons like rapiers in a 
fencing match. If anything more than mere fencing takes 
place the results must be serious for one or both of the com- 
batants, that is certain. The old Arctic explorer, Scoresby, having 
taken a large skate out of a Narwhal, believed, perhaps from the 
appearance of wounds in the fish, that the tusk was used as a spear 
Photo bu) [H. Dixon, 
to impale such living prey. But having spitted the fish, how was A WARNING ATTITUDE. 
it removed from the spear? Perhaps by a violent and sudden The Cobra, when on, the point of 
« ” 5 9 attack, raises its head and puffs out 
back-water ’? movement—a reversal of its engines, so to speak. its neck to display its peculiarly terri- 
Another strange feature of this creature is the asymmetry of its i" marlones: 
skull, the nostrils leading to blowholes being twisted strongly towards the left. It might be supposed 
that this was due to the great development of the socket for the tusk, which makes the jaw-bone of 
this side much larger than that of the right, where there is no tusk. But the same twist is found 
when both tusks are equally developed ; and, further, it occurs again in other species, like the bottle- 
nosed whale, which is toothless. 
WARNING COLOURS 
BY E. B. POULTON, F.R.S. 
ANIMALS of all kinds, in temperate countries such as our own as well as in the tropics, are, as a rule, 
coloured so that they harmonize with their surroundings and are concealed. Among these, certain 
exceptions stand out with startling distinctness, species which seem to be coloured so as to attract 
attention. Walking along a hedgerow in summer, we shall fail to see numbers of caterpillars 
resembling the twigs or green 
foliage, and moths hidden 
on the bark or among dead 
leaves; but the red, black- 
spotted ladybirds or the 
cream-coloured caterpillars of 
the Magpie moth, with their 
black and orange marks, 
will at once arrest the at- 
tention. The explanation 
of these conspicuous colours 
has a very interesting his- 
tory. Darwin was thinking 
over the bright colours which 
adorn so many male animals, 
Photo bu) ss : [A. S. Rudland. d a8 t 1 4 
THE SKUNK. an Was Working ou D1S 
Protected by an offensive fluid secreted in certain glands, the Skunk is marked in celebrated theory of Sexual 
such a way that it can be seen—and avoided—by even the most unwary. Selection, when he was 
