A CONTRIBUTION TO THE STUDY OF THE SCOTTISH SKULL. 423 



pendicular varied from 16 to 21 mm., with a mean of 18 '5 mm. ; in 17 Australians 

 the perpendicular varied from 11 to 25 mm., with a mean of 18 mm. ; in 16 Scottish 

 the perpendicular varied from 16 to 24 mm., with a mean of 19'8 mm. The frontal 

 projection in the Australian showed the smallest mean, then with a slightly 

 larger mean came the Tasmanian, while the mean value was distinctly larger in the 

 Scottish series. 



He also pointed out that a very much greater portion of the perpendicular was 

 taken up by the thickness of the bone in the Australian than in the European. The 

 mean height shown by those results for the Scottish series is about 2 mm. less 

 than that shown by the mean of my series, and it shows that the height of the 

 Australian figured by Klaatsch as 13 mm. can by no means be taken to represent 

 the average height of the frontal arc in that type of skull. This is confirmed by 

 the measurements in a series of 90 Australian skulls, where the frontal arc height 

 varied from 13 to 28 mm., with a mean value of 19 '30 mm. On the whole, how- 

 ever, the height of the frontal arc appears to be decidedly less in the Australian than 

 in the Scottish. 



Turner gives for the parietal arc height in the Tasmanian a mean value of 

 24'1 mm., the range being 21 to 26 mm., which, he says, closely corresponded with 

 the value for the frontal arc height as measured from the nasi-bregmatic line, and 

 showed that in their entirety these bones had almost similar curvatures. The same 

 relationship holds between the corresponding heights in the Scottish series, and con- 

 firms the belief that these bones have almost similar curvatures in the Scottish skull, 

 which was shown previously by the near approach to equality exhibited by the size 

 of the frontal and parietal angles. For a larger series of 90 Australian skulls the 

 height of the parietal arc varied from 16 to 30 mm., with a mean value of 22 '91 mm., 

 i.e. distinctly greater than the mean frontal arc height. 



Turner (47) gives for the occipital arc height of the Tasmanian a range of 

 3 to 10 mm., with a mean value of 7'1 mm. The mean value for the occipital arc 

 height in 90 Australian crania was 5 '78 mm., with a range from 3 to 12 mm. In our 

 series the lambda-inion chord was very variable, and the above height varied from 

 3 to 19 mm., which is a marked illustration of Turner's statement "that it would 

 be possible to arrange a series of British skulls in which variations from a well- 

 marked occipital bulging to a form closely approaching that of the Neanderthal 

 could be seen." This would seem even possible in such a homogeneous series as 

 the present one. 



The index devised by Klaatsch for the arcs, i.e. —r^ — -, — ^— : T — , has been 



J length ot chord 



calculated for Tasmanian and Australian series of skulls by Buchner (61 ). We can 



compare their values with those found in the Scottish series in a table such as the 



following : — 



