Man's place in nature, and other anthropological essays . dAvhich may be termed the craniofacial angle, is ex-tremely obtuse, amounting, in the case of the Beaver, toat least 150°. But if a series of sections of mammalian skulls, inter-mediate between a Rodent and a Man (Fig. 29,) beexamined, it will be found that in the higher crania thebasicranial axis becomes shorter relatively to the cere-bral length; that the ^ olfactory angle and ^^ occipitalangle become more obtuse; and that the craniofacialangle, becomes more acute by the bending down, as itwere, of the facial axis upon the cranial axi
Man's place in nature, and other anthropological essays . dAvhich may be termed the craniofacial angle, is ex-tremely obtuse, amounting, in the case of the Beaver, toat least 150°. But if a series of sections of mammalian skulls, inter-mediate between a Rodent and a Man (Fig. 29,) beexamined, it will be found that in the higher crania thebasicranial axis becomes shorter relatively to the cere-bral length; that the ^ olfactory angle and ^^ occipitalangle become more obtuse; and that the craniofacialangle, becomes more acute by the bending down, as itwere, of the facial axis upon the cranial axis. At thesame time, the roof of the cranium becomes more andmore arched, to allow of the increasing height of thecerebral hemispheres, which is eminently characteristi?-of man, as well as of that backward extension, beyond 166 MANS PLACE IN NATURE. the cerebellum, which reaches its maximum in theSouth American Monkeys. So that, at last, in thehuman skull (Fig. 30,) the cerebral length is betweentwice and thrice as great as the length of the basicranial. Fig. 30.—Sections of orthognathous (light contour) andprognathous (dark contour) skulls, one-third of the naturalsize, a b, Basicranial axis; & c, & c, plane of the occipital:foramen; d d\ hinder end of the palatine bone; e e\ front endof the upper jaw; T T, insertion of the tentorium. ON SOME FOSSIL REMAINS OF MAN. 16^ axis; the olfactory plane is 20° or 30° on the underside of that axis; the occipital angle, instead of beingless than 90°, is as much as 150° or 160° ; the cranio-facial angle may be 90° or less, and the vertical heightof the skull may have a large proportion to its length. It will be obvious, from an inspection of the dia-grams, that the basicranial axis is, in the ascendingseries of Mammalia, a relatively fixed line, on whichthe bones of the sides and roof of the cranial cavity, andof the face, may be said to revolve downwards and for-wards or backwards, according to their position. Thearc described by
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Keywords: ., bookcentury1800, bookdecade1890, booksubj, booksubjecthumanbeings
