A CONTRIBUTION TO THE STUDY OF TIIE SCOTTISH SKULL. 411 



Schwalbe's angle, according to Sollas (46), is determined by three factors : — 



1. The choice of a base line. 



2. The angular position of the bregma. 



3. The altitudinal index of the skull. 



All three combine to give it a low value in the Australian skull and in the 

 Neanderthal group. 



For Schwalbe's angle or the bregma angle, Turner gives for Scottish skulls, 6 in 

 number, a variation of 54°-58°, with a mean of 56° ; for Tasmanian, 7 in number, a 

 variation of 54°-60°, with" a mean value of 57"1°. Klaatsch gives for Tasmanians, 

 8 in number, a variation of 54°-59°, with a mean of 57"3° ; Berry gives for unsexed 

 Tasmanians, 45 in number, a variation of from 51 '5° to 64°, with a mean of 56°. In 

 this Scottish series of 100 there is a variation of .from 50° to 63°, with a mean of 

 56'33° ; for the Australian Klaatsch gives a variation of from 51° to 62°, with a 

 mean value of 5 7 '5°. The Scottish skull thus shows a lower value than the Tasmanian, 

 according to Turner's figures, whereas, according to the figures derived from the 

 larger numbers, the Tasmanian and the Scottish show a practically identical mean 

 angle, while the Australian shows the highest value. Sollas (46), however, gives for 

 the Australian an angle of 48 '3°, which is lower than the Scottish mean angle and is 

 the position one would a priori expect the Australian to occupy, and this is con- 

 firmed by Berry's results (59) for a series of 100 Australian crania (unsexed). In 

 this the bregma angle varies from 49° to 60°, with a mean value of 54'7°. 



Turner (47), making use of the nasi-tentorial plane to avoid the variability in the 

 glabella, found in his examination of the angle between the nasi-bregmatic and nasi- 

 tentorial lines that the Australians showed the highest angle, the Tasmanians the 

 smallest, and the Scottish an angle intermediate in value. 



Berry's dioptrographic tracings have permitted me to estimate the upper glabella 

 angle in 90 Australian crania, and its mean value in this long series was practically 

 equal to that shown in Buchner's complete series of Tasmanian skulls, while the 

 mean angle in the Scottish series was lower in value to the extent of 2°. With 

 a more sloping frontal bone we would have expected, as Klaatsch believed to be 

 the case, that the angle above mentioned would be smaller in the Australian than 

 in the European (as represented by the Scottish skull). 



Schwalbe's view regarding the elevation of the frontal bone, where its upper 

 border is said to move upwards and forwards in modern, as compared with palaeolithic, 

 man, the resulting displacement of the bregma and more vertical direction of the 

 frontal bone, has been criticised by Cunningham (48), who raised several objections to 

 the bregma angle : — 



1. Because the glabella was so variable. 



2. Because the upper end of the frontal was affected by changes in the other 



bones of the vault independent of those due to elevation or depression of 



the frontal bone. 

 TRANS. ROY. SOC. EDIN., VOL. LI, PART II (NO. 9). 58 



