154 ANTHROPOID APES. 



present in the orang, but they are of small size and 

 separated into detached bundles. The pyramidalis 

 nasi may be traced in every instance, especially in 

 the gorilla (Figs. 50, 4) and in the orang. It is not 

 so strongly developed in the chimpanzee and gibbon, 

 but is not absent in these apes, nor in those which 

 are not anthropoid, such as the baboon, and ateles, 

 or climbing ape. 



I myself follow the original division of the muscles 

 into those which belong to the nostril and upper 

 lip, in accordance with the principles of Duchenne, 

 Darwin, Gamba,* and others, and I do so the more 

 readily, since it is impossible not to perceive the 

 manifold and lively mimetic action which takes place 

 in this particular region of an ape's head. The 

 distinct action of the levator labii superioris alseque 

 nasi, the dilation of the nostrils, the function of a 

 strongly developed levator anguli oris, are especially 

 characteristic of the gorilla ; but they are also per- 

 ceptible in the chimpanzee and gibbon. The orang's 

 face is the least mobile. I observed that in the 

 gorilla the risorius was very long, branching slightly 

 in the fore-part of the corner of the mouth, and 

 behind into three distinct wide bundles. The lowest 

 bundle covered the platysma myoides, but could 

 not be regarded as part of the latter. In one chim- 

 panzee I found that the risorius was slightly de- 

 veloped, and in other animals of that species I failed 

 to trace it at all. Alix and Gratiolet represent the 



* J)udhenTLe'B Micanismedelaphysiognomiehumaine. Darwin's 

 Expression of the amotions. Gamba's Lexioni di cmatomo-fisiologia 

 a/ppUcata alle arti helle. 



