486 THE ANATOMT OF VEETEBRATED ANIMALS. 



The joremolars have three roots in the ujjper jaw, two in the 

 lower. The crowns of the middle molars, above, have four 

 cusps, and an oblique ridge which extends from the antero- 

 external to the postero-intemal cusp ; and those of the middle 

 molar, below, have five cusjds, as in Man. The crown of the 

 anterior premolar in the lower jaw is pointed, and has a 

 long, sharp, oblique anterior edge as in the Cynomorpha. 



In the Gibbons, the permanent canine emerges contem- 

 poraneously with, or before, the last molar ; but, in the other 

 Antliropoviorplia, the last permanent canine is cut, ordinarily, 

 only after the appearance of the last molar. 



In the Orang the circumvallate papilla9 of the tongue are 

 an'anged in a V> as in Man. In the Chimpanzee they are 

 disposed like a T, with the top turned forwards. The 

 Chimpanzee and the Siamang have an uvula, but the Orang 

 has none. The stomach of the Chimpanzee is very like that 

 of Man; but in the Orang the organ is more elongated, 

 with a round cardiac and more tubular pyloric portion. 

 An appendix vermiformis is found in the caecum of all four 

 genera. In the Chimpanzee and Gorilla, the origin of the 

 great arieries from the arch of the aorta takes place as in 

 Man. In the Orang, they are sometimes disposed as in 

 Man; while in other specimens the left carotid comes off 

 from the innominata, and only the subclavian of the left 

 side arises directly from the aorta. In Hylobates, the latter 

 arrangement appears to obtain. 



The kidney has only a single papilla in Hylobates and 

 Pithecus. 



Only one species of Hylobates, namely, the Siamang, is 

 known to possess a laiyngeal sac. This is globular, and 

 communicates by two apertures, situated in the thyrohyoid 

 membrane, with the larynx. In the Orang, Chimpanzee, 

 and Gorilla, enormous air sacs result from the dilatation 

 of the lateral ventricles of the larynx. These dilatations 

 extend down, in front of the throat, on to the thorax and 

 even into the axilias, and sometimes open into one another 

 in the middle line. 



In the adult male Chimpanzee the penis is small and 



