478 THE ANATOMY OF VERTEBEATED ANIMALS. 



are wide, and become more or less closely connected with 

 the ilia. The last lumbar vertebra may become ankylosed 

 with the sacrum in the Gorilla. All these conditions of 

 the last lumbar vertebra are occasionally met with in Man. 



The sacrum is broad, and contains not fewer than five 

 ankylosed vertebrae, 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 disguised 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 other Apes, but the sagittal and lamb- 

 doidal cfests are strong. In the old male Gorilla the sagittal 

 and lambdoidal crests, and the supraorbital ridges, are 

 alike enormous. The frontal sinuses are large, and extend 

 into the brow ridges both in tbe Gorilla and Chimpanzee. 

 The jaws are largest in proportion to the brain case in the 

 Gorilla and the Orang ; smallest in some varieties of Chim- 

 panzee. 



In all the Anthropomorpha the transverse is much less 

 than the longitiidinal 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 upwards and outwards. 

 The occipital foramen is situated in the posterior third of 

 the base of the skull, and looks obliquely backwards and 

 downwards. The frontals meet in the base of the skull 

 over the ethmo-presphenoidal suture in the Gibbons and in 

 the Gorilla, as in the Baboons ; but not in the Chimpanzee 

 or the Orang. The alisphenoids i;nite suturally with the 

 parietals, as is the rule in Man, in the Gibbons and (usually) 

 in the Orangs ; but, in the Chimpanzee, the squamosal unites 

 with the frontal and separates the alisphenoidfrom theparie- 



