ANATOMICAL STRUCTXTEE OF ANTHROPOID APES. 181 



do not always agree together, the muscular system 

 of authropoids is on the whole very like that of 

 man. It displays, especially in the lower limbs, 

 peculiarities of structure which render them capable 

 of walking in an upright position, and others again 

 which they have in common with the lower animals, 

 but on the whole the anthropoid characteristics of 

 the muscular system of these animals are predomi- 

 nant. 



The digestive system of authropoids likewise 

 affords interesting points of comparison. The cavity 

 of the mouth is, as we have seen, bordered by large 

 and flexible lips. The mucous membrane of the 

 mouth and the gums are flesh-coloured ; they 

 assume a darker colour in older animals, and are 

 then sometimes marked with spots of a bluish or 

 brownish grey. Ehlers describes, as a peculiarity 

 in the mucous membrane of the mouths of the 

 gorilla and chimpanzee, that there are what he calls 

 buccal folds, which pass on both sides from the fore 

 surface of the upper and lower jaw into the mucous 

 membrane of the cheeks, and are of the height of 

 the canine teeth.* I have myself only observed 

 these folds in the gorilla, of which an illustration is 

 given in Fig. 3, and not in any other specimen. I 

 have observed scarcely any indications of these 

 folds in other anthropoids, and then only of such a 

 doubtful nature that I am not disposed to regard 

 the circumstance as of any special significance. 

 A small band on the upper and lower lips, sometimes 



* Beiirdge zur Kenntniss des Gorilla U7id Chimpanse, p. 32, plate 

 ii. 6g. 3. 



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