THE ANTHROPOMORPHA. 405 



bifurcated in the Chimpanzee, but this human character does 

 not appear in the others. 



In the Gibbons there are usually eighteen dorso-lumbar 

 vertebriE ; but in the other Anthropomorpha the number is 

 ordinarily seventeen, as in Man, or may be reduced to sixteen. 

 The Orang has the human number of twelve pairs of ribs , 

 but the Chimpanzee and Gorilla have thirteen, and the Gib- 

 bons may possess fourteen pairs of ribs. The thorax is wide, 

 and the sternum broad and flat. In the Orang it may ossify 

 fiom a double longitudinal series of centres, as sometimes hap- 

 pens in Man. 



In the Gibbons the transverse processes of the last lumbar 

 vertebra are not exceptionally broad, and do not unite with 

 the iha. But in both the Chimpanzee and Gorilla they are 

 wide, and become more or less closely connected with the ilia. 

 The last lumbar vertebra may become anchylosed with the 

 sacrum in the Gorilla. All these conditions of the last lum- 

 bar vertebra are occasionally met with in Man. 



The sacrum is broad, and contains not fewer than five 

 anchylosed vertebrce, but its length always exceeds its breadth 

 (whereas its breadth is equal to, or exceeds, its length, in Man), 

 and its anterior curvature is but slight. The short coccyx is 

 made up of not more than four or five vertebrae. In the skull, 

 the proper form of the brain-case is always more or less dis- 

 guised in the adult males, by the development of crests for 

 muscular attachment, or of the orbits and the supraorbital 

 ridges. In the Gibbons and Chimpanzees, the latter are 

 large, but the sagittal crest is absent, and the lambdoidal 

 small. In the Orang, the brow-ridges are small, so that the 

 true form of the forehead is seen better than in the othei 

 Apes, but the sagittal and lambdoidal crests are strong. In 

 the old male Gorilla the sagittal and lambdoidal crests, and 

 the supraorbital ridges, are alike enormous. The frontal si- 

 nuses are large, and extend into the brow-ridges both in the 

 Gorilla and Chimpanzee. The jaws are largest in proportion 

 to the brain-case in the Gorilla and the Orang ; smallest in 

 some varieties of Chimpanzee. 



In all the Anthropomorpha the transverse is much less 

 than the longitudinal diameter of the cranial cavity. The 

 roofs of the orbits project into the frontal portion of the brain- 

 case, and diminish its capacity by causing its floor to slope 

 from the middle line obliquely upward and outward. The oc- 

 cipital foramen is situated in the posterior third of the base 

 of the skull, and looks obliquely backward and downward. 



