94 
TERTIARY VERTEBRATA OF THE FATCM. 
tliin alveolar border. About 2’5 centimetres behind tlie large tooth are two small 
alveoli for a double-rooted incisor (?'. 2), and behind this again the remains of another 
double-rooted tooth, the third incisor (i. 3). The presence of these peculiar double- 
rooted incisor-teeth seems to show that the same causes, whatever they may be, which 
gave rise to a double-rooted premolariform canine also affect the two posterior incisors, 
so that all the teeth behind the first incisor practically form a series of cheek-teeth. 
Comparison of this premaxilla and its contained tusk with the premaxilla and 
incisor of a recent Ily racoid show that, as in Saqhatherimn magnum^ the two are 
closely similar in most respects. The presence of the two posterior incisors is just 
what might be expected in this early form, the remarkable thing being not the 
difference between the Eocene forms and recent types but their great resemblance, 
which shows that, so far as the front of the skull is concerned, the older forms were 
almost as peculiar as the modern ones. 
Among the specimens collected by Mr. Beadnell in 1903 is the cranial portion of 
a skull (text-fig. 39) which, from its resemblance to the corresponding part of the skull 
of Saghatherium antigumn, may reasonably be referred to a Ilyracoid, and from its 
size most probably belongs to the present species. 
The occipital condyles (coiid.) are large and sharply truncated at their upper border. 
The foramen magnum [f.m.) is roughly quadrate in outline. Above and external to 
the condyles there is on either side a deep depression separating them from the 
strongly developed paroccipital processes which project below their level. The 
occipital surface widens out a little above the condyles and its up[)er border forms 
the middle portion of a high prominent lambdoiclal crest, which is continued 
downwards and outwards on to the squamosal and is continuous with the upper edge 
of the zygomatic process of that bone. Just below the lambdoidal crest the occipital 
surface bears in the middle line a roughened ridge flanked by two smaller lateral 
ones ; this portion of the surface slopes somewhat backwards. Between the upper 
edge of the paroccipital process and the squamosal there is a slit-like foramen lying 
immediately beneath the lambdoidal crest ; laterally and external to the slit the 
anterior face of the ])aroccipital region of the exoccipital is closely apposed to the 
posterior face of a nearly vertical ridge of the squamosal, the two limiting a 
w'ell-markcd groove. Between the just-mentioned vertical ridge and the upper 
border of the zygomatic process is a triangular area, at the bottom (d* which the 
auditory opening must have been ; the anterior border of this de[)ression is formed by 
a prominent postgieuoid process (pgl.). 
There is a strong sagittal crest (s.c.) running forwards from the lambdoidal ridge till 
it bifurcates. The temporal ridges (iKOt'b.) thus formed run out on to the ])ostorior 
borders of the supraorbital processes. The lu'ain-case is strongly rounded and slightly 
contracted a little behind the orbits. The frontal region ( fr.) is very broad and flat, and 
closely resembles the same ])ortion of the skull of iSaghalheriuni and IJgrax (rrocavin). 
