ling
fishes on the look-out for a meal. A broad expanse of white would at
once betray it to the enemy. No colour is developed on the under
surface, for it would be a waste of energy to produce colour for a
surface that was kept constantly concealed from view.

[Illustration: Fig. 2.--Full-grown Sole.]

Although, in our picture, all these fish can be seen quite plainly, in
real life they are quite hard to find. The young, being well-nigh
transparent as glass, are almost invisible as they float in the water;
while later, when these wanderings cease, and they settle down to a
quiet life, the dark colour forms an equally invisible covering.

W. P. PYCRAFT, F.Z.S., A.L.S.

[Illustration: Prairie Dogs.]

THE PRAIRIE DOG.

The little animal which is commonly called the prairie dog is not a dog
at all, but one of the Marmot family, which is to be found in Europe and
Asia, as well as in America. The only reason for calling it a dog is
that, when excited, it utters a cry which is very like the barking of a
puppy.

This little marmot is rather larger than a good-sized rat, and rather
like that animal in general appearance. Its colour is a red-brown,
speckled with grey and black hairs above, but whitish-grey below. The
tip of its tail is tufted with black hair, which is rather long and
bushy.

The prairie dog lives out on the vast, treeless prairies of North
America, where immense numbers of them congregate together, and make
what are called dog-villages, or towns. The marmots burrow in the ground
like rabbits, and sometimes the country is undermined with their burrows
for a space of several miles. Each marmot, as it builds its burrow,
throws out the loosened earth into a little hillock by the mouth of its
burrow, and when it has nothing better to do it sits upon the top of its
mound, and watches what is going on. At the sight of a stranger, or an
enemy, the marmots, sitting on their mounds, begin to bark and chatter,
jerking up their little tails with every effort until they feel that
they are hardly safe any longer; then they drop into their holes, and,
turning round, pop out their heads to watch a little longer. If the
intruder comes too near, however, they withdraw altogether, and seek
safety in the depths of the burrows. But they are very inquisitive, and
if they are not harmed they soon put out their heads again to see what
is taking place. Hunters who have walked through a dog-village, hoping
to get a shot