160 ANTHROPOID APES. 



lower fibres tend far backward, and are in connection 

 with the deltoid muscle covering a segment of the 

 capsular ligament. This muscle wrinkles the skin 

 of the neck, and helps to draw down the lower jaw. 

 In cases in which it extends far in an upward direc- 

 tion, as in those we have cited, it affects the lateral 

 extension of the middle and lower skin on the faces 

 of these animals, as well as the grinning contortion 

 of the corner of the mouth. It may also have to do 

 with the grumbling sound issuing from the throat- 

 pouch, which is uttered by the animal when agitated, 

 as he rapidly opens and closes his mouth. 



The strong sterno-cleido-mastoid muscle found in 

 these animals, and especially in the orang and 

 gibbon, can be divided without difficulty into a 

 sternal and clavicular portion. The two portions 

 diverge from each other in a downward direction. 

 As Bischoff justly states, a muscle not hitherto ob- 

 served in man may be traced in all four species of 

 anthropoids, a muscle which extends from the ex- 

 ternal part of the clavi<-le to the transverse process 

 of the first cervical vertebra. Bischoff has called it 

 tlie musculus omocervicalis. It is found in other 

 apes, although the site of its origin varies, some- 

 times occurring on the spine of the scapula. Our 

 jMunich anatomist differs from Huxley in regarding 

 this muscle as " a brilliant proof of the relation of 

 all apes with each other." I give this assertion 

 without further comment. 



The muscles which extend between the head, 

 sternum, and clavicle, together with the muscles of 

 the acromion process of the scapula, make an ex- 



