PRIMATES 



479 



mammalian features as plantigrade gait and five toes, and signs 

 of arboreal ancestry such as a large clavicle and the opposable 

 thumb, he has his own specialisations, which are largely con- 



FiG. 369. — A human skull, seen from the right side. 



-From Cunningham 



23. Frontal bone. 



24. Pterion, 



25. Temporal fossa. 



26. Great wing of sphenoid. 



27. Zygomatic bone. 



28. Zygomatico-facial foramen. 



29. Lacrimal bone. 



30. Nasal bone. 



31. Infra -orbital foramen. 



32. Piriform aperture and an- 



terior nasal spine. 



nected with the upright stance. To make the best of his nine-pin- 

 like shape and consequent unstable equihbrium he has developed 

 a sigmoid curve in the backbone, the large gluteal muscles of 

 the buttocks to prevent the body falling inwards when he stands 

 on one leg, and the arch of the foot, with heel behind the point 



