h, but contents himself with levying a tax
on the foods which enter the cavity. It is a case of commensalism of
which there are very numerous examples. Other cases may be mentioned
which are still further removed from parasitism. Among these may be
mentioned the birds who relieve large mammals of their vermin.

One of them, the Red-beaked Buffalo bird (_Buphaga erythrorhyncha_),
lives in Abyssinia. This bird is insectivorous. He has remarked that
the ruminants constitute baits for flies; therefore he never leaves
these animals, hops about on their backs and delivers them from
annoying parasites; the buffaloes, who recognise this service, allow
the bird to wander quietly over their hide. The _Buphaga_, who gives
himself up entirely to this kind of chase, is often called the
Beef-eater. He is only found in the society of flocks, of camels,
buffaloes, or oxen. He settles on the back, legs, and snouts of these
living baits. They remain passive even when he opens the skin in order
to draw out the flies' larva; they know the benefit of this little
operation. The patience of the oxen is certainly due to custom, for it
is observed that herds which are not used to this bird manifest great
terror when he prepares to alight on them, so that they even take
flight from this small aggressor.

Sometimes it is not easy to understand the advantages derived by the
animal from the conditions in which he is usually found. Thus, for
example, there is a fish, the _Polyprion cernium_, which accompanies
driftwood on which Barnacles have fixed themselves. Yet the remains of
these Crustaceans are never found in his stomach, and it is known on
the contrary that he lives exclusively on other small fish. It is
possible that these find their food in fragments of wood at the
expense of the barnacles, and that therefore the _Polyprion_ which
hunts them is always near driftwood thus garnished.

_Methods of utilising the captured game._--Frequently it is not enough
for the animal to obtain possession of his prey. Before making his
meal it is still necessary to find a method of making use of it,
either because the eatable parts are buried in a thick shell which he
is unable to break, or because he has captured a creature which rolls
itself into a ball and bristles its plumes. Here are some of the more
curious practices followed in such cases.

Sometimes it is a question of carrying off a round fruit which offers
no prominence to take hold of. The Red