Some animals

have a gall-bladder close to the liver, and others
have not. Of viviparous quadrupeds the deer is without the organ, as
also the roe, the horse, the mule, the ass, the seal, and some kinds
of pigs. Of deer those that are called Achainae appear to have gall in
their tail, but what is so called does resemble gall in colour, though
it is not so completely fluid, and the organ internally resembles a
spleen.

However, without any exception, stags are found to have maggots
living inside the head, and the habitat of these creatures is in the
hollow underneath the root of the tongue and in the neighbourhood of
the vertebra to which the head is attached. These creatures are as
large as the largest grubs; they grow all together in a cluster, and
they are usually about twenty in number.