ON SOME FOSSIL REMAINS OF MAN 325 



or 160 ; the cranio-facial angle may be 90 or less, and 

 the vertical height of the skull may have a large propor- 

 tion to its length. 



It will be obvious, from an inspection of the diagrams, 

 that the basicranial axis is, in the ascending series of 

 Mammalia, a relatively fixed line, on which the bones of 

 the sides and roof of the cranial cavity, and of the face, 

 may be said to revolve downwards and forwards or back- 

 wards, according to their position. The arc described by 

 any one bone or plane, however, is not by any means 

 always in proportion to the arc described by another. 



Now comes the important question, can we discern, 

 between the lowest and the highest forms of the human 

 cranium anything answering, in however slight a degree, 

 to this revolution of the side and roof bones of the skull 

 upon the basicranial axis observed upon so great a scale 

 in the mammalian series ? Numerous observations lead 

 me to believe that we must answer this question in the 

 affirmative. 



The diagrams in Figure 29 are reduced from very care- 

 fully made diagrams of sections of four skulls, two round 

 and orthognathous, two long and prognathous, taken 

 longitudinally and vertically, through the middle. The 

 sectional diagrams have then been superimposed, in such 

 a manner, that the basal axes of the skulls coincide by 

 their anterior ends, and in their direction. The devia- 

 tions of the rest of the contours (which represent the 

 interior of the skulls only) show the differences of the 

 skulls from one another, when these axes are regarded as 

 relatively fixed lines. 



The dark contours are those of an Australian and of a 

 Negro skull : the light contours are those of a Tartar 

 skull, in the Museum of the Royal College of Surgeons ; 

 and of a well developed round skull from a cemetery in 

 Constantinople, of uncertain race, in my own possession. 



It appears, at once, from these views, that the prog- 

 nathous skulls, so far as their jaws are concerned, do 

 really differ from the orthognathous in much the same 

 way as, though to a far less degree than, the skulls of the 

 lower mammals differ from those of Man. Furthermore, 

 the plane of the occipital foramen (b c) forms a somewhat 

 smaller angle with the axis in these particular prognathous 

 skulls than in the orthognathous ; and the like may be 

 slightly true of the perforated plate of the ethmoid 



