" There is another dull beast which, from the point of view of the mere systematist, seems as far removed from those that wear hoofs as it could be, but the philosopher, considering the point at which it has arrived, rather than the route by which it got there, will class it with them, for its idea of life is just theirs turned topsy-turvy.

Intermediate forms occur, connecting one group with another in a manner sadly perplexing to systematists, except to those who have ceased to expect absolute limitations in Nature.