THE CHIMPANZEES AND ORANGS. 87 



DESCRIPTIONS OF THE PLATES. 

 (All the figures are of the natural size.) 



PLATE XXVI. 

 Base of the cranium of the Troglodytes Gorilla from the River Danger. 



PLATE XXVII. 

 Summit of the same cranium. 



PLATE XXVIII. 

 Inside view of the same cranium, vertically and longitudinally bisected. 



PLATE XXIX. 



Inside views of similarly bisected skulls of — fig. 1. an adult, and fig. 2. an immature 

 male, Pithecus Satyrus, from Borneo. 



PLATE XXX. 



Fig. 1 . Inside view of a similarly bisected skull of a male Australian Papuan. 



2. Horizontal section through the superorbital ridge of the skull of a male Tasma- 

 nian Papuan. 



(The same figures, letters and lines indicate the same parts in each Plate.) 



1. Basioccipital. 



2. Exoccipital. 



jp. Jugular process. 



j. Jugular foramen. 



cf. Condyloid fossa. 



5. Basisphenoid. 



6. Alisphenoid. 



n. Fossa for ' natiform protuberance.' 



7. Parietal. 



8. Mastoid. 



m. Mastoid process. 



