132 
TEETIARY VEETEBRATA OF THE FAYCm. 
condyles. Its body is keeled ventrally and it unites with the basisphenoid at about 
tlie level of the ghuioid cavity for the mandible : the line of union with the hasi~ 
sphenoid {i>sp.) is marked by a fairly prominent transverse ridge. The lateral border of 
the median limb is separated from the anterior border of the lateral portion by a 
sharp notch, through which the hypoglossal nerve probably passed, there being, as 
in the later Troboscidea, no condylar foramen. 
With tlie possible exception of a small portion of their inner ends, the whole of the 
occipital condyles are formed by the exoccijntals [exo.). The condyles themselves are 
much larger and project fuVther behind the skull than in Elephas, in which their 
articular surface seems to look mainly downwards and to project very little beyond 
the rest of the exoccipital bones. Here, on the other hand, the condyles are so 
sharply marked off from the rest of the bone as to be almost pedunculate. Their 
articular surface extends far on to the dorsal surface, and they are very strongly convex 
from above downwards — in fact, roughly speaking, they may be said to form about 
two-thirds of tlie surface of a cylinder — and at the same time they are slightly convex 
from side to side. From the form of the condyles, therefore, it would appear that the 
range of movement allowed to the skull in an up-and-down direction must have been 
very great, while that from side to side was comparatively restricted. 
The foramen magnum {f.m.) is oval in outline and does not look downwards so 
much as in Elephas, mainly owing to the fact that the posterior border of the basi- 
occipital is less deeply notched. Ventrally and laterally the surface of the exoccipitals 
runs forwards in a gentle curve to join the post-tympanic flange {ptp.) of the squamosal. 
On the ventral surface near the union with the squamosal the exoccipital bears a blunt 
prominence {pp.), which is the only representative of the paroccipital process, and is 
therefore homologous with the thin plate-like ventral process of the bone described 
in the skull of Mceritherium. The upper portion of the bone above the condyles and 
the foramen magnum slopes forwards, and the two elements meet in the middle 
line, separating the supraoccipital from the foramen magnum by a distance of about 
5 centimetres. 
The precise boundaries of the supraoccipital [soc.) are indistinct. In the middle 
line it, like the upper portion of the exoccipitals, is inclined forwards ; above it is 
hollowed out by a great median fossa, the floor of which is greatly roughened and is 
obscurely divided into halves by a slight median ridge. I'his fossa is one of the most 
characteristic ]ieculiarities of the skull of the later Elephants, but in Faheomasfotlon 
it is far more sharply defined, probably, ff)r the most ])art, on account of the smaller 
develo[)ment of the cellular tissue of the rest of the bone. 'I’he sides of the fossa an* 
formed by broadly rounded vertical ridges. The su])erior and su})ero-lateral ])ortions 
of the bone occupying the position of the lambdoidal crest are unfortunately broken 
away, but it can be seen that in conjunction with tlie neighhouring squamosals and 
parietals the body of the bone is excavated by a series of large cellular cavities, 
