If the Ruminants are distinct from the Rodents, and if that distinction rests upon a whole system of massive differences that there can be no question of attenuating, it is because they possess different kinds of dentition, different digestive systems, differently formed extremities and nails; it is because they cannot capture the same kinds of food, or deal with it in the same way; it is because they do not have to digest the same forms of nourishment.