248 
TEliTIAKY VEIITEBRATA OF THE FAYtM. 
anterior root of pm. 3, and beneath it a smaller aperture. The alveolar border is 
broad : in front are the large single alveoli for the canine, winch is much larger than 
the incisors, and for tlie first premolar, behind and to the outer side of which are 
shallow ])its for the points of the lower teeth. Then come the alveoli for the large 
double-rooted 2 ; behind and to the inner side of the posterior root of this and 
the remaining ])remolars are deep fossae for the reception of the points of the lower 
teeth. The third and fourth premolars are large three-rooted teeth which will be 
described below. The lirst molar is beneath the orbit ; it had two or three roots, there 
being doidjt as to whether the wide posterior root is merely grooved or actually divided 
into two. Whether any other molars were present is uncertain, but probably there was 
at least one more. The palatine surface of the maxilla is raised into a broad ridge 
as far back as the hinder end of the second premolar; then it flattens out to form 
the palate and unites behind with the palatines in an oblique suture : there is 
a pair of small posterior palatine foramina. The inner face of the bone forming the 
wall of the nasal passage is strongly concave from above downwards : on this face 
towards the anterior end of the bone is a strong longitudinal ridge increasing in 
height backwards, perhaps representing the maxillo-turbinal. The lachrymal [la.) 
is a small element forming a slight projection at the anterior border of the orbit 
and wedged in between the frontal, the jugal, and the maxilla. The jugal (ju.) 
is a comparatively stout bar of bone, the anterior end of which is thrust 
between the lachrymal and the backward prolongation of the maxilla; it forms 
the ventral border of the orbit. Its free portion is slightly flattened from above 
downwards in front and from side to side posteriorly ; its pointed posterior end 
underlies the strong zygomatic process of the squamosal {sq.). This bone is very 
large and forms the whole of the great lateral expansion of the hinder part of the 
skull. Posteriorly it unites with the supraoccipital above, then with the exoccipital, 
and below this again with the mastoid portion of the periotic, l^ixternal to this 
it forms a broad concave surface, looking backwards and forming the lateral region 
of the posterior face of the skull. The lambdoidal crest is continued on the 
squamosal, running downwards in an S-shaped curve, then becoming continuous with 
the sharp upper border of the zygomatic process. 4'he upper edge of the bone unites 
with the supraoccipital and in front of this with the parietal, the line of union with 
which runs downwards and forwards and is raised into a moderately jirominent ridge. 
Its anterior border is produced forwards as a sharp-edged shelf, the lower face of 
which is occupied by the glenoid articulation for the mandible. The large zygomatic 
prominence {zyq.) projects considerably beyond the rest of the bone; })osteriorly it 
is produced downwards into a large flange-like postglenoid jirocess. The anterior 
free portion of the zygomatic jirocu'ss is convex externally, its upper edge being 
continuous jiosteriorly with the lambdoidal crest, as already mentioned ; the jugal 
runs back beneath it as far as the anterior boundary of the glenoid surhice. 
