THE EVOLUTION OF THE EYEBROW REGION OF THE FOREHEAD. 311 



EXPLANATION OF PLATES. 



Plate I. 



Fig. 14. Skull of a young Macaeus cy clops. The superciliary eminences are seen in the form of two 

 isolated, oval, slightly raised areas. (Type I.) 



Fig. 15. Skull of Macaeus rhesus. Superciliary eminence strongly marked, elongated, and separated 

 from the supraorbital margin in its whole length. (Type I.) 



Fig. 16. Skull of adult chimpanzee (Goodsir series). Torus supraorbitalis well marked, but it will be 

 noticed that the superciliary eminence has not been completely absorbed into it. The general outline of the 

 superciliary eminence is distinct, and it also presents a distinctive texture. (Type II. merging into Type III.) 



Fig. 17. Skull of a young chacma baboon (Cynocephalus porcarius, Turner series). The superciliary 

 eminences stand clear of the supraorbital margin. (Type I.) 



Fig. 18. Skull of an adult baboon (species doubtful). The superciliary eminences by their inner parts 

 are confluent with the inner parts of the supraorbital margins. (Type II.) 



Fig. 19. Skull of an adult Anubis baboon {Cynocephalus anubis). Shows a nearer approach to the fusion 

 of the superciliary and supraorbital elements of the region than in fig. 18. 



Plate II. 



Fig. 20. New South Wales cranium (xxix. B. 1, Turner series). Tori supraorbital es well marked. 

 (Type III.) a, supratrochlear grooves ; b, supraorbital notches. 



Fig. 21. New South Wales cranium (xxix. B. 1). Orbital aspect of the frontal bone, a, supratrochlear 

 grooves ; b, supraorbital notches. Note how the interorbital region is pinched in between the two supra- 

 trochlear nerves. 



Fig. 22. Australian skull from the Queensland district (xxix. A. 10, Turner series). Tori supraorbitales 

 with a steep and highly curved forehead. (Type III.) 



Plate III. 



Fig. 23. Skull of a native of New Hebrides Islands (xxvii. C. 3, Turner series). Type II. of the supra- 

 orbital region. Contrast with fig. 18, PI. I. 



Fig. 24. Skull of native of Australia from Riverina district (xxix. B. 12, Turner series). Very pro- 

 jecting supraorbital region ; transition condition between Type II. and Type III. 



TRANS. ROY. SOC. EDIN., VOL. XLVI. PART II. (NO. 12). 47 



