2

Common to all animals are the organs whereby they take food and the organs where into they take it; and these are either identical with one another, or are diverse in the ways above specified: to wit, either identical in form, or varying in respect of excess or defect, or resembling one another analogically, or differing in position.

Furthermore, the great majority of animals have other organs
besides these in common, whereby they discharge the residuum of
their food: I say, the great majority, for this statement does not
apply to all. And, by the way, the organ whereby food is taken in is
called the mouth, and the organ whereinto it is taken, the belly;
the remainder of the alimentary system has a great variety of names.