It can thus obtain food beyond the reach of the other Ungulata or hoofed animals inhabiting the same country; and this must be a great advantage to it during dearths.

The Niata cattle in South America show us how small a difference in structure may make, during such periods, a great difference in preserving an animal's life.

These cattle can browse as well as others on grass, but from the projection of the lower jaw they cannot, during the often recurrent droughts, browse on the twigs of trees, reeds, etc.

, to which food the common cattle and horses are then driven; so that at these times the Niatas perish, if not fed by their owners.

Before coming to Mr. Mivart's objections, it may be well to explain once again how natural selection will act in all ordinary cases.