CONSTANT DIFFERENTIAL GROWTH-RATIOS 19 



Values of Cranium-length and Face-length in the Baboon Papio 

 porcarius at Different Sizes (from Zuckerman, 1926) (Figs. 9, 10) 



No. of Cases 



1 



4 

 7 

 3 

 6 



4 



The growth-coefficient of face-length on cranium-length for 

 Classes 2-5 is about 4-25, a very high figure. The curve 

 shows irregularities at both ends. 



Fig. 10. — Baboon skulls of various sizes, to show the increase in relative size 



of facial region with absolute size of skull. 



1, new-born; 2, juvenile (with milk dentition); 3, adult female; 4, adult male. 



