LIST OF ILLUSTRATIONS xxiii 



Figure Page 



205. Gibbon. Level of the emergence of the sixth cranial nerve 436 



206. Gibbon. Level through the middle of the pons 437 



207. Gibbon. Level of the emergence of the trochlear nerve 438 



208. Gibbon. Level of the inferior colliculus 440 



200, 210. Gibbon. Level of the superior colliculus 442, 443 



211. Gibbon. Level of the optic chiasm 444 



212. Gibbon. Level of the anterior commissure 445 



213. Ventral surface of gray matter of brain stem, Hylobates hoolock (cofor) 449 



214. Dorsal surface of gray matter of brain stem, Hylobates hoolock (co/or) 451 



215. Lateral surface of gray matter of brain stem, Hylobates hoolock (color) .... 453 



216. Habitat group, orang-outang, Sadong River, Borneo 481 



217. Orang-outang, erect posture, showmg disproportion of arms and legs 482 



218. Orang-outang, showing anthropomorphous tendencies in head and face 483 



219-222. Hand and foot of the orang-outang 484, 485 



223A and B. Dorsal surface of brain, orang-outang 488, 489 



224A and B. Base of brain, orang-outang 490, 491 



225A and B. Left lateral surface of brain, orang-outang 494, 495 



226a and b. Right lateral surface of brain, orang-outang 496, 497 



227. Ventral surface of brain stem of orang-outang 500 



228. Dorsal surface of brain stem, orang-outang 501 



229. Orang-outang. Level of the pyramidal decussation 502 



230. Orang-outang. Level of the caudal extremity of the dorsal sensory nuclei .... 505 



231. Orang-outang. Level of the caudal extremity of the inferior olive 508 



232. Orang-outang. Level through middle of inferior olive 511 



233. Orang-outang. Level of the vestibular nuclei 514 



234. Orang-outang. Level of the cerebellar nuclei 516 



235. Orang-outang. Level near caudal limits of pons, emergent sixth nerve fibers. . 518 



236. Orang-outang. Level of the middle of the pons Varolii 521 



237. Orang-outang. Level of emergence of trochlear nerve 522 



238. Orang-outang. Level of the inferior colliculus 524 



239. Orang-outang. Level of the superior colliculus 526 



240. Orang-outang. Level of the optic chiasm 530 



241. Ventral surface of gray matter of brain stem, Simla satyrus (color) 535 



242. Dorsal surface of gray matter of brain stem, Simla satyrus (color) 537 



243. Lateral surface of gray matter of brain stem, Simla satyrus (color) 539 



244. Habitat group, chimpanzee 54-7 



245. 246. Chimpanzee Susie 548, 549 



247-250. Hand and foot of chimpanzee 552, 553 



251A and B. Dorsal surface of brain, chimpanzee 560, 561 



252A and B. Base of brain, chimpanzee 562, 563 



253A and B. Left lateral surface of brain, chimpanzee 568, 569 



254. Ventral surface of the brain stem, chimpanzee 5-2 



255. Dorsal surface of brain stem, chimpanzee 5-3 



