A CONTRIBUTION TO THE STUDY OF THE SCOTTISH SKULL. 



435 



we find that increased capacity is associated, first, with a certain increase in maximum 

 length, the hinder part of the skull being chiefly affected ; second, with marked increase 

 in breadth, affecting frontal, parietal, and occipital regions, so that the vault retains its 

 ellipsoidal or long oval shape ; third, with increase in height, affecting more especially 

 the hinder part of the vault. The distinction is well brought out in fig. 15, in which 

 the mean Scottish and mean Australian contours are superimposed and oriented on 

 the glabella-inion line instead of the glabella-lambda line as in fig. 10. The part 

 taken by the occipital segment in the lengthening of the sagittal arc was also proved 

 in the section on correlation, and the facts may possibly be of interest in connection 

 with the feature in brain evolution which has been pointed out by Elliot Smith, viz. 



Br 



/ 







• CH 



^^~~~^--~~> 



ft 



r^ 













jS - - " X y 





X 



\^ ' / - *- s ^x 



































/ / Ss 









/ / // 







V / ^*\ N 



/ ' ys 























' / % ^*\ \ 



























/ /* 







'/ x ^ 



yr 



L 





/ / x X 









1 

 ll 











^v ^"--~-_ 

























Sx 









^x 









































v O\ 



















s > 





= r=-=^ r=r ^ 



— H 



Ba 



Fig. 15. — Diagram showing sagittal cranial contours and quadrilateral figures of mean West Scottish 

 and mean Australian skulls superimposed — the glabella-inion line as base. 



G., glabella; Br., bregma; C.H., calvarial height ; L., lambda ; I., inion ; Ba., basion. 



West Scottish— continuous line. Australian — interrupted line. 



the increase in the higher type of brain of the great association area between the sen- 

 sory, the auditory, and visual areas, by which the regions on the lateral aspect of the 

 occipital lobe have been pushed backwards and finally over on to the mesial surface. 

 As pointed out in the section on Klaatsch's method, individual skulls may be 

 found in the Scottish series showing characters which approach the lower type ; one 

 such skull, number 20, may be referred to in this connection. It has a cubic capacity 

 of 1520 c.c, it is very long, moderately broad, but coincidently very low, being 

 only, as regards calvarial height, 1 mm. higher than the Australian mean and 1 mm. 

 lower than the Tasmanian. In the norma lateralis it has quite a strong resemblance 

 to an Australian skull, and though it has not the great frontal torus it has a very 

 projecting inion and distinct occipital torus. Its breadth, however, is outside the 

 highest range of the Australian in this direction. By the peculiar combination of 



the three dimensions the measurements fall, in all but five of the tables published by 

 TRANS. ROY. SOC. EDIN., VOL. LI, PART II (NO. 9). 61 



