MUSCULAR SYSTEM. 19 



tensor proprius digiti indicis is the more remarkable, as, through 

 this, the Apes are deprived of the power of mimicking the action 

 of pointing, and the index must always in their case be extended 

 along with the rest of the fingers. The foot of the Apes is, as 

 regards its muscular movements, more like the hand ; its interossei 

 muscles are arranged like those of the same name in the human 

 hand, and enable the toes to spread and approximate, in their 

 chief movement, the act of climbing. There is found further, in the 

 foot of the Apes, an abductor longus pollicis and minimi digiti. 

 Other arrangements of the muscular system in the Apes depend 

 upon their incapability of maintaining the erect posture. Certain 

 flexor muscles of the legs, as the biceps, sartorius, gracilis, semiten- 

 dinosus, are invariably inserted very low down into the leg, so that 

 the knee always appears bent in front, and the limb can not be com- 

 pletely extended. The rotator muscles of the femur, such as those 

 of the buttocks, are much more feebly developed in the Apes, than 

 in Man. The abdominal muscles are, on the contrary, much 

 stronger in the Apes, in order to sustain more easily the weight of 

 the viscera, in progressing upon all fours, and the femoral and 

 inguinal rings have much wider openings. The scapula of the Apes 

 has much stronger and more powerful muscles than that of Man, to 

 prevent its luxation ; and it is furnished with a peculiar protractor 

 muscle, which is wanting in Man. The cervical muscles are in 

 like manner much stronger, and implanted higher up upon the 

 cranium, to prevent the head sinking downward. The latissimus 

 dorsi gives off a singular muscular slip, which is attached by tendon 

 to the olecranon process, and is especially developed in the long- 

 armed Apes, where it serves to sling the whole arm very rapidly 

 and powerfully forward, a movement which is of the greatest im- 

 portance for dexterously grasping remote branches while in the act 

 of climbing. The tailed Apes, those even provided with a short 

 stump, e. g. Inuus ecaudatus, have a caudal muscle very highly de- 

 veloped, and divided into many bundles, which act as elevators, later- 

 alizers, and depressors of the tail. In the prehensile-tailed Apes, 

 the tail serves even as a fifth hand, and the flexor muscles are 

 hence very much developed. In Man the facial muscles are much 

 more separated, and subdivided into a greater number of fasciculi 

 than in the Apes, whence arises that manifold power of expression, 

 which serves as a reflex of the internal workings of the mind. The 

 Apes have only a pair of strong muscular masses which surround the 



