INTRODUCTION. 
xviii 
condition of the sjicciincns examined is not favourable to its preservation. The canine 
and tlie first ])reniolars are lost; the other preraolars are evidently undergoing 
reduction, hnt at the same time the last lias become hilophodont. The molars are 
all trilo])liodont, each transverse crest consisting of at least two distinct tubercles ; 
there is also a tendency to the addition of another posterior ridge from the cingulum. 
One notable point about the molar series is the sudden enlargement of the second 
and third true molars, compared with the teeth in front. This is accompanied by 
llie considerable development of cellular tissue in the posterior part of the maxilla 
and the neighbonring bones, and appears to be the first indication of the great 
increase in tlie size of the posterior molars found in later types. This increase in 
the size of the maxilla, which is probably correlated with the general tendency of the 
bones of the posterior part of the skull to develop diploe, seems almost as if it were 
a preparation for the subsequent changes in the teeth, but, on the other hand, it is 
])ossible that the increase in their size may be in part a consequence of possessing 
more room in which to develop. 
As already noted, the mandible is greatly elongated in the symphysial region, and 
its ascending ramus slopes backwards, both modifications tending to increase the 
distance the animal could reach with its lower incisors. Of these there is a single 
pair (the second) projecting forwards from the symphysis: the canines and first and 
second premolars are lost; the other premolars and molars are generally similar to 
those of the upper jaw. In the vertebral column the axis still has a peg-like 
odontoid process and a comparatively long centrum, though the centra of the posterior 
cervicals are much shortened. The limb-bones, so far as known, are closely similar, 
except in size, to those of FAephas. 
In general appearance Falaomastodon must have resembled a small rather long- 
necked Elephant, tlie most notalde difference being that the trunk, instead of being 
freely flexible, was supported by, and formed the upper covering of, the elongated 
mandibidar symphysis ; its extremity, however, may have been free and to some degree 
prehensile. 
The further history of this group can only be briefly summarised here (see Phil, 
'rrans. 19G b, 1903, p. 99). The next form, TetrnheJodon mKjustidens from the European 
Power Miocene, has the symphysis still more elongated and the narial opening shifted 
f urther back. At the same time tlie molars, or at h ast the posterior ones, are greatly 
increased in size and possess more transverse ridges. Ihere are three milk-molars 
in both jaws, and the jiosterior two are succeeded in the normal way by premolars; 
