e were only
five cross-ridges--on the biggest--and these ridges tend to divide
into separate cones (Fig. 8). So here, too, we are approaching the
ordinary mammals, of which we may keep the pig and the tapir in mind
as samples. But the Mastodons still had the great trunk and huge tusks
of the elephants.

Next we must look at Tetrabelodon (Fig. 12), and it is this creature
which has really revealed the history of the strange metamorphosis by
which elephants were produced. The Tetrabelodon is known as "the
long-jawed mastodon," because, as was shown in a wonderfully
well-preserved skeleton from the lower Pliocene of the centre of
France, set up in the Paris Museum, it had a lower jaw of enormous
length, ending in two large horizontally directed teeth (Fig. 12).
Instead of a lower jaw a foot long, as in an elephant or in the common
kind of mastodon--this long-jawed kind had a lower jaw 5 feet or 6
feet long! The tusks of the upper jaw were large, and nearly
horizontal in direction, bent downwards a little on each side of the
long lower jaw. This lower jaw seemed incomprehensible, almost a
monstrosity--until it occurred to me that it exactly corresponds to
the elongated upper lip and nose which we call the elephant's
trunk--and that the trunk of "Tetrabelodon" must have rested on his
long lower jaw. In descending to Tetrabelodon we leave behind us the
elephants with hanging unsupported trunk; the lower jaw here is of
sufficient length to support the great trunk. When the lower jaw
shortened in the later mastodons and elephants the trunk did not
shorten too, but remained free and depending, capable of large
movement and of grasping with its extremity. Photographs, casts, and
actual specimens of the extraordinary skull of the long-jawed mastodon
or Tetrabelodon and of the creatures mentioned below may be seen in
the Natural History Museum.

Lastly we have the wonderful series of discoveries made about twelve
years ago by Dr. Andrews (of the Natural History Museum) of
elephant-like creatures in the upper Eocene of the Fayoum Desert of
Egypt. Palaeomastodon (the name given by Dr. Andrews to one of them) is
a "pig-like" mastodon, with an elongated, bony face, the tusks of
moderate size, and the lower jaw not projecting more than a few inches
beyond them, so that the proboscis is quite short and rests well on it
(Fig. 13). This animal had six moderate sized grinders (molars or
cheek-teeth) on each side of each jaw in position s