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1829, the knowledge of the anthropoid apes was limited to these 

 three forms. It had been suspected that the pongo might be the 

 adult form of the orang; but Cuvier, pointing to its distinctive 

 characters, suggested that it could hardly be the same species. The 

 facial angle of the small red orang of Borneo, and of the small 

 black chimpanzee of Africa, brought them, from the predominant 

 cranium, and small size of the jaws and small teeth, nearer than 

 any other known mammalian animal to the human species, par- 

 ticularly to the lower, or negro forms. It was evident, from the 

 examination of these small chimpanzees and orangs, that they 

 were the young of some large species of ape. The small size and 

 number of their teeth, (there being, in some of the smaller speci- 

 mens, only twenty, like the number of deciduous teeth in the 

 human species,) and the intervals between those teeth, all showed 

 them to be of the first or deciduous series. In 1835 I availed 

 myself of the rich materials in regard to these animals collected 

 about that time by the Zoological Society, to investigate the state 

 of dentition, especially that of the permanent teeth which might be 

 hidden in the substance of the jaws, of both the immature orang- 

 outang and the chimpanzee, and I found that the germs of those 

 teeth in the orang-outang agreed in size with the permanent teeth 

 that were developed in the jaws of a species of the pongo of Wurmb, 

 which Sir Stamford Raffles had presented to the museum of the 

 College of Surgeons some years before. Specimens of orangs since 

 acquired, of an intermediate age, have shown the progressive 

 change of the dentition. 



In the substance of the jaw were found the germs of the great 

 canines, and of large bicuspid teeth ; foreshowing the changes that 

 must take place when the jaw is sufficiently enlarged to receive 

 permanent teeth of this kind; and, when the rest of the cranium is 

 modified, concomitantly, for the attachment of muscles to work the 

 jaw so armed, denoting that all these changes must result in the 

 acquisition of characters such as are presented by the skulls of the 

 large pongo, or Bornean baboon-like ape. The specific identity of 

 the pongo with certain of the young orang-outangs, was thus 

 satisfactorily made out, and is now admitted by all naturalists. 

 With regard to the chimpanzee, the germs of similarly propor- 

 tioned large teeth were also discovered in the jaws, indicating, in 

 like manner, that it must be the young of a much larger species 

 of ape. 



The principal osteological characters of the chimpanzee and 



