OR OSSEOUS SYSTEM. 115 



and the ordinary sutures of the human cranium continue 

 permanent, as in the higher forms of quadrumana. The 

 sagittal suture often traverses the frontal bone, and the an- 

 terior frontals are sometimes seen separate. The temporal 

 fossa is small, the zygomatic arch feeble, the condyles of the 

 lower jaw and their glenoid cavities flat, the lachrymal bones 

 extend downwards from the orbits, and are perforated on 

 their facial surface, and the nasal bones, unlike those of 

 higher quadrumana, are broad, long, straight longitudinally, 

 and form an expanded arch in their transverse direction, as 

 in carnivora and other inferior tribes. The ramus of the 

 lower jaw is still very short, its condyles are nearly as low 

 as the alveoli of the teeth, and the coronoid processes rise 

 high through the zygomatic arches. The inferior incisor 

 teeth, four in number, as in the simise and in man, project 

 straight from the lower jaw, as those of a kangaroo, and 

 this direction is seen also in the stenops, the galago, and the 

 lichanotus. The face and entire head become shorter as 

 we ascend through these genera to the true simiae of the old 

 and new continents. In the simiee the lamdoidal, the sagit- 

 tal, the squamous, and the coronal sutures advance forwards 

 on the cranium more and more as the cerebral centres and 

 the cranial cavity enlarge, and the face becomes proportion- 

 ally small. As the muzzle shortens, the facial angle en- 

 creases by the elevation and expansion of the frontal bone, 

 and by this shortening of the jaws less space is afforded 

 for numerous molar teeth. The orbits approximate, assume 

 an anterior and parallel direction, separated only by a narrow 

 ethmoid, and their communication with the temporal fossae 

 is cut off by an osseous partition formed by the extension 

 of the frontal and malar bones. The temporal fossa be- 

 comes reduced in size, the zygomatic arch short and straight, 

 the condyloid articulation of the lower jaw flat and free, 

 the lachrymal bone confined to the orbit, and the nasal 

 bones flat, narrow, short, and often anchylosed together. 

 The intermaxillaries continue permanently separate up to the 

 orangs, and the incisors, four above and below, as in man, 

 continue more inclined forwards than in the human jaws. 

 The canine teeth, as instruments of prehension and of de- 

 fence, continue large and projecting, and the sharp tuber- 

 cles of the molar teeth of the insectivorous and nocturnal 



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