298 ON THE SKULL OF ORYCTEROPUS GAUDRYI.  [Feb. 18, 
position of the condyle, which is borne upon a much shorter pedicle 
and has a more horizontal articular surface. 
The minute structure of the teeth is precisely as in O. capensis, 
so that they give no indications of the possible origin of their 
peculiar character. 
In the left maxilla six teeth remain in place, and in front of them 
is an empty alveolus; on the right there are five teeth and two 
alveoli. The most anterior tooth preserved is pm.3 (counting 
from behind forward); this is small and laterally compressed, its 
flat crown slopes downward and forward. The next is similar, 
but less compressed. The hindermost premolar is a stout simple 
tooth ; its worn crown consists of two flat surfaces meeting in an 
angle and forming a transverse ridge. The two first molars are very 
similar to those of the recent species, but the last (m.*) is rather 
different. In the living forms it is somewhat variable in shape, 
but usually consists of a single column and is nearly circular in 
section; in one skull from Somaliland, it is, however, oval in 
section and shows traces, at least on the outer side, of division 
into two lobes, the hinder being much the smaller. The circular 
type of tooth evidently results from the reduction of the hinder 
lobe, which in the fossil is only a little smaller than the anterior 
one, from which it is separated by a well-marked vertical groove on 
the outer side and a less distinct one on the inner. In a young 
skull of a recent species, in which the last molars are only just 
coming into use, they are distinctly bilobed, so that the upper part 
of the crown of the unworn tooth resembles in form the worn 
molar of the Pliocene species. 
In the mandible six teeth are preserved on both sides. The two 
anterior ones are much compressed; the next is stouter and its 
grinding surfaces form a transverse ridge. The first two molars 
are similar to those of the living species: the third (m..,) is clearly 
bilobed and is nearly as long asm.,. In the recent species the 
division into columns is distinct only on the inner side, and the tooth 
is much shorter from before backward than the preceding one, 
The dimensions of the skull and mandible are :— 
Skull. 
Width between ends of postorbital processes.. 53 millim. 
Outside width at postglenoid processes ...... GOiui -= 
Width of cranium behind postorbital processes 36 ,, 
Greatest width of occipital surface.......... ‘spe e 
Height of foramen magnum .............. 1S: es 
Width ‘ Pe taicsie Be Nias. Sion, bt Rega 
Distance between postorbitalprocessandzygoma 17 _ ,, 
Mandible. 
Height at coronoid process ................ 65 millim. 
yi > CRIS ORE BOS oe cies ww ate OF he. 
Height of ramus behind last molar ........ LG: 24, 
i » in front of first molar....,. 12 — ,, 
