I 3 2 ELEMENTARY ANATOMY. [LESS. 



tion of the foramen magnum. Nevertheless, its maximum 

 of development in Mammals is not found in him, but in the 

 little American Ape Chrysothrix. 



In the great majority of instances the occiput is not visible 

 when the skull is looked at from beneath, or a projecting 

 lambdoidal ridge is seen in the place of the lambdoidal 

 suture. Occasionally, however (as in the Woodcock), the 

 occipital surface is largely visible, the foramen magnum 

 being situated far forwards. 



A peculiar character may exist in the occiput, as can be 

 seen in the Indian Elephant, where there is a deep and sharp 

 double depression with a median, vertical ridge. This de- 

 pression curiously resembles that in which the cribriform 

 plate is placed in so many Mammals, the median ridge 

 reminding one of the crista galli. This occipital fossa is for 

 the reception of a strong ligament, which helps to sustain the 

 very weighty skull. 



An anterior condyloid foramen may be entirely absent, as 

 in Fishes, in which class there is no distinct hypoglossal 

 nerve. 



Great depending para-mastoid (or par-occipital) processes 

 may replace the mastoids, as in the Horse and the Capybara. 



The anterior region of the skull of adult man presents an 

 appearance but very rarely approached by that of any brute. 

 Nevertheless, certain of the American Monkeys (e.g. Pithecia 

 and Nyctipithecus) present a close general resemblance, 

 which is also to be plainly seen in the young Chimpanzee, 

 and still better in the young Orang Utan. 



Generally speaking, owing to the prolongation of the 

 muzzle, the skull is so much foreshortened when viewed in 

 front that its actual shape can be very little seen. The same 

 apparent distortion also occurs in extremely depressed or 

 compressed skulls. 



Although the rounded frontal region of man is all but 

 peculiar to him, his superciliary projections are but rudiments 

 of what may be developed even in closely allied forms, as 

 we see in the Gorilla, the superciliary ridges of which are 

 enormous. Very generally the orbital fossae are placed so 

 laterally that, unlike those of man, they are very little seen 

 when the skull is looked at in front. On the other hand, they 

 may approximate more closely than in him, as in many 

 Monkeys. As has been said in describing the superior 

 maxillary bone, the infra-orbital foramen may be replaced by 

 a great aperture, or by a number of small apertures. The 



