172 ANTHROPOID APES. 



ment. In the orang, the lower fibres of the short 

 abductor of the thumb likewise have their origin 

 in the sesamoid bone, while the central fibres 

 again start from the anterior annular ligament. 

 The upper fibres are strong, and are inserted into 

 the base of the first metacarpal bone. In a dissec- 

 tion of the orang the flexor longus pollicis sent 

 a thin, tendinous expansion on to the bone. This 

 sesamoid bone is also found in the gorilla, although 

 Duvernoy and Rosenberg do not appear to be aware 

 of its existence.* 



In the palm of the gorilla's hand there is a short 

 abductor, a short bicipital flexor, an opponens, and 

 an abductor of the thumb. The longer belly 

 of the short flexor extending in a more radial direc- 

 tion, and in connection with the opponens, is only 

 slightly developed. In the muscular system of a 

 gorilla's little finger we may observe an abductor, 

 a short flexor, and an opponens. The palm of the 

 chimpanzee displays a short abductor, an opponens, 

 a short bicipital flexor, and an adductor of the 

 thumb ; also an abductor, a short flexor, and an 

 opponens of the little finger. In the orang I observed 

 a short abductor, a short flexor with two bellies, 

 an opponens, and an adductor of the thumb. In 

 addition to the short flexor of the thumb, Langer 

 and BischofF describe another short, independent 

 muscle, representing the long flexor, and attached 

 to the second phalanx, but I have not myself ascer- 

 tained the existence of this muscle. The same 



* Hartmann in Archiv. fur Anatomie, by Eeicbart and Du Bois- 

 Eeymond, p. 743 (1875) ; p. 636 (1876). 



