198 HUMAN FOSSILS. in 



cording 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 dis- 

 cern, between the lowest and the highest forms of 

 the human cranium anything answering, in how- 

 ever 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 mam- 

 malian series? Numerous observations lead me to 

 believe that we must answer this question in the 

 affirmative. 



The diagrams in Fig. 30 are reduced from 

 very carefully 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 an- 

 terior ends, and in their direction. The deviations 

 of the rest of the contours (which represent the in- 

 terior 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 

 Eoyal College of Surgeons; and of a well de- 

 veloped round skull from a cemetery in Con- 



