A CONTRIBUTION TO THE STUDY OF THE SCOTTISH SKULL. 441 



If we regard the size of the angle as a quantity which either increases or decreases 

 throughout the series, and correlate it with the basi-nasal length, we find that the 

 coefficient of correlation is +'16 + '065, i.e. it is positive and sensible but not of great 

 magnitude, so that while there is a tendency for the spheno-ethmoidal angle to in- 

 crease when the basi-nasal length increases, such a tendency is not at all marked. 

 Correlating the greatest length of the skull with the spheno-ethmoidal angle gives 

 a coefficient of correlation '053 ± '067 positive but practically negligible considering 

 the size of the probable error, so that the size of the angle in the series seems to be 

 independent of the length of the skull, although the latter, as has been previously 

 stated, shows a high correlation with the basi-nasal length. Both the middle base 



Fig. 20. — Impression of median sagittal section of skull, N.B. series F ; cubic capacity 2060 c.c. 

 Spheno-ethmoidal angle, 156° ; spheno-maxillary angle, 88° ; foramino-basilar angle, 153°. 



and the anterior base, i.e. the boundary lines of the angle above mentioned, vary con- 

 siderably in their degree of inclination to the Frankfurt horizontal plane, and the 

 angle which the anterior base forms with this plane is more variable than that 

 formed by the middle base. 



Apparently there is some doubt as to the value to be attached to the above angle, 

 as has been stated by Duckworth in regard to the foramino-basal angle, and that 

 the former should be used like the latter in comparisons of the Hominidae with the 

 Simiidse and lower forms rather than for the comparative study of members of 

 different races in the human family. 



B. Spheno-Maxillary Angle (a). 



This angle in the series of 98 varied from 67° to 101°, with a mean value of 8 4 "29° ; 

 the S.D. was 5 '43 and the V. was 6 '44. In Turner's group of 5 the mean value was 

 8 6 '4°, slightly greater than the mean value shown by our series. Duckworth gives 



