SOME REMARKS ON THE PLEISTOCENE MAMMALIA. 11
and numerous plates (E. primigenius or true mammoth). E.
trogontherii and the true mammoth are also characterised by the
peculiar curvature of their tusks. Nevertheless, the immense
series of molar teeth now at our disposal shows that the succes-
sion and divergence into two types is not so simple as it appears.
It was long ago recognised that the mammoth of the north was
adapted by fine-plated molars to feed on hard vegetation, while
along the southern-most limit of its range both in the Old and
in the New World it was adapted by wider-plated molars to feed
on the more succulent vegetation among which it lived. There
can be no doubt that these two forms of mammoth were con-
temporaneous geographical races. Soergel25 has even suggested
that the straight-tusked E. antiquus and the curved-tusked ances-
tral mammoth E. trogontherii were characteristic of forest and
steppe respectively, and were less distinct in western Europe
than further east because our humid oceanic climate caused
forest and steppe conditions to be less well separated here than
they were further inland. In any case, we are continually puzzled
with molars which are not so clearly characterised as to be easily
named, and the difficulties of the subject will not be solved until
many complete skeletons are available. It is sad to note that
the specimen from Ilford in the British Museum (Nat. Hist.)
is still the only known skull of a mammoth from England, and
no skeleton has yet been preserved. It is even more unfortunate
that E. antiquus is known solely by one skeleton, without the
cranium, which was dug up at Upnor, near Chatham, and is
now being prepared and mounted in the British Museum (Nat.
Hist.).
I fear these observations are somewhat desultory, but I hope
they are sufficient to illustrate the difficulties of the subject to
which I referred at the outset. They show the importance of
recording always the exact geological conditions under which the
remains of Pleistocene mammals occur. They justify such in-
tensive research as that which Mr. Hazzledine Warren, for
instance, has accomplished at Ponder's End and Clacton. They
form the apology of a palaeontologist for the hesitation which he
often feels in deducing conclusions from the collections before
him.
25 W. Soergel, "Elephas trogontherii Pohl. and Elephas antiquus Falc., ihre Stam-
mesgeschichte und ihre Bedeitung fur die Gliederung des deutschen Diluviums," Pal-
aeontographica, vol. lx. (1913), pp. 1-114, pls. i-iii.