SKELETON OF BIMANA. 



i59 



floor of the cavity to the level of the lower teeth, when the man- 

 dibular ramus rests on a horizontal plane. The supranasal ridge is 

 not so produced as in the Gorilla. The zygomatic arch is shorter 

 and more slender; the mandible shows both the angle and the 

 ' mentum,' instead of being rounded off at both ends as in the 

 Gorilla. But the most important differences are brought out in 

 the base-views, figs. 370 and 359. In the lowest as in the high- 

 est Human race, the foramen magnum is placed nearer the centre 

 of the base of the skull, the anterior end of the condyles reach- 

 ing the transverse line which equally bisects the base. The con- 

 dyles are relatively larger. The mastoids are developed into pro- 

 cesses of the size and form which gave rise to the name. The 

 zygomatic arches are in the anterior half of this view of the skull, 

 but are opposite the middle third in the Gorilla. The stylo -hyals 

 are anchylosed, and are supported anteriorly by a ridge from the 

 tympanic called the ' vaginal process.' The eustachian process of 

 the petrosal is shorter. A short styliform process is developed 

 from the lower and outer angle of the alisphenoid. The glenoid 

 cavity for the mandibular condyle is deeper, and is formed behind 

 by the tympanic. There is also a low postglenoid prominence. 

 The bony palate is much shorter, but is proportionally deeper 

 and broader, and the teeth are arranged in a full semielliptic con- 

 tour without any natural interspace, the croAvns being of equal 

 leno'th. In the Gorilla the alveoli of the molars and canine 

 of one side are in a straight line, parallel with those of the other 

 side. 



As a general rule the form of the 

 Human cranium, seen from above, 

 fig. 371, is a full oval, with the 

 small end forward, and the largest 

 diameter across the ' parietal emi- 

 nences,' fig. 375, c. The bones seen 

 in fig. 371 are the superoccipital, o, 

 the parietals, p, and the frontal, F ; 

 the sutures are the ' lambdoid,' c, 

 the ' sagittal,' h, and ' coronal,' a. 



In fig. 372, O marks the expanded 

 and outwardly convex superoccipital, 

 articulated by the ' lambdoid' suture, 

 c,with the parietal, and by the 'mast- 

 occipital ' suture with the mastoid : 



g marks the poster-inferior angle of the parietal, P, which unites 

 by the 'mast-occipital' suture with the mastoid: this angle 



371 



or upper view of human 

 cranium. 



