i64 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



preserved jaw of Spy the angle is 107°, if measured 

 from the inferior symphysial border, or 90° if meas- 



Fig, 45. — Vertical sections of symphysis mandibuli of. gorilla (Fig, /4;, and 

 orang {Fig. B)^ of chimpanzee (Fig. Cj, of Spy man No. i (Fig, Z?), and Spy man 

 No. 2 (Fig. E), From Fraipont and Lohest, 



ured from the inferior border of the ramus. There 

 is no chin in the jaw of the Spy race, and the large 

 angle approaches without nearly equaling that of the 



