566 GEOLOGICAL SURVEY OF THE TERRITORIES. 



principal extent posterior to tbe zygomatic arcb, and is in form like a 

 trough, the inferior edge being recurved from the squamosal process to 

 the summit of the 0(;cipital crest. It is narrow within the zygomatic 

 arch, wliich is short, inclosing a space whose length is less than one- 

 fourth that of the cranium. 



The occiintal bone extends but a short distance on each side of the 

 condyles, and is separated ftom tbe nuigtoid by an irregular suture, 

 which is pierced by a large mastoid foramen. On the inferior face, near 

 to each condyle, and one-third the distance from its inner extremity, is a 

 X)osterior condyloid foramen, isolated by a narrow bar from the extremity 

 of the foramen lacerum posierius. The paramastoid process is repre- 

 sented by a small tuberosity, and the mastoid by a rather larger one, 

 some distance anterior to it. 



The meatus atiditorivs opens upwards just below the external ridge of 

 the tem[)oral fossa, and at a little distance behind the i)ost-glenoid pro- 

 cess. Its canal contracts rapidly, and extends upwards and backwards 

 towards the labyrinth. It is separated from the foramen lacerum by but 

 a thin wall, and if there was an expansion of the cavum Ujmimm^ it must 

 have been exceedingly small, owing to the close approximation of the 

 mastoid to the basi-occipital and sphenoid at this j)oint. The labyrinth 

 is lodged in a petrous mass opposite the occipito-mastoid suture, and the 

 canals are small. 



The hasi-occipital contracts anteriorly, and with the splienoid forms an 

 uninterrupted boundary of the foramen laeerum. This terminates oppo- 

 site to tlie posterior boundary of the external meatus, and gives rise to a 

 wide, shallow groove, which extends anteriorly between the i)terygoid 

 ala and the post-glenoid process, and turning outwards round the latter, 

 grooves it. Opposite to the post-glenoid process, andjust i)osterior to the 

 end of the pterygoid, a small foramen enters, which is probably the fora- 

 men ovale. Almost continuous with it is a canal which pierces the base 

 of the pterygoid longitudinally, and issues in an excavation of its exter- 

 nal face near the sphenoid. 



The pterygoids are remarkable for their great length, inclosing, as they 

 do, with the palatine process, a deep, narrow, trench -like fossa, which 

 measures almost the entire length of the zygomatic fossa. Processes of 

 the sphenoid contribute to these walls, (which are thus double.) and the 

 S{)heuoid roof is strongly concave. The aUsphenoid is elongate antero- 

 l)osteriorly, and is principally in contact sui)eriorly with the frontal ; an- 

 teriorly it has a short suture with the lachrymal. Almost its entire length 

 is traversed by a shallow groove which terminates in a small foramen 

 opticum^ opposite to a point marking the posterior third of the zygomatic 

 fossa. The foramen rotwuhnn issues as usual between the alisphenoid 

 and tbe pterygoid, but is considerably anterior as well as inferior to the 

 f. oplicmn. I cannot determine whether the orbitosphenoid is distinct. 



The laelirymal is a large bone, of a triangular outliue, the shorter 

 side being inferior. It is entirely on the inner iace of the orbit, and, 

 as in the elephant, se})arates the frontal and maxillary by its superior 

 prolongation. Its interior border is slightly notched in front by the 

 h\v<^e foramen infraorhitale posterius^ awd the anterior is deeply emar- 

 giuate, i^assing behind the small /. lachrymale. 



The palate is reuiarkable for its length and narrowness. Its roof is 

 chiefly composed of the maxillaries, but a very short j)ortion is formed l)y 

 the [)alatine i)lates of the o. o. palatina. These are produced into a 

 median j>oint behind, between the nares, and exteriorly form the inner 

 wall of the postnareal trough for a considerable distance. The closely 

 united maxillaries form the outer wall for a short distance, being pro- 



