QUADRUMANA. 



calcaneum is very strong, and the hinder 

 thumb is, like the hallux of man, the thickest 

 of all the toes. In the other monkeys of the 

 Old World, the hinder hand loses entirely its 

 analogy with the foot of the human subject. 

 The tarsus is long and narrow, and the hallux 

 acquires more and more the form of a small 

 thumb, removed from the other toes, and 

 giving to the foot some resemblance with the 

 hand ; from which the name of four-handed 

 Mammalia or Qitadrumana is derived. 



MYOLOGY. If the osteology of the Mon- 

 keys of the Old World affords us the oppor- 

 tunity of making .some interesting remarks, 

 their myology will certainly seem not less 

 important. But it will be almost impossible 

 to give an accurate description of their 

 muscles in the small space allowed to me. I 

 therefore think it proper to confine myself to 

 those statements, by which the same gradual 

 inferiority as in the bony framework may be 

 confirmed, and I beg leave to refer to my 

 Rech. d'Anat. comp. sur le Chimpanse for a 

 more minute description. One of the very 

 striking peculiarities of the myology of the 

 monkeys is the existence of a distinct pla- 

 tysma myoides, which I found in all those I 

 had the opportunity to dissect. It is an im- 

 portant conformity with the structure o{man, 

 in whom this muscle represents the larger 

 subcutaneous muscles of the other mammalia. 



The sterna cleido-mastoideus offers an in- 

 cipient indication of a lower station, by the 

 clavicular fascicle being wanting in the Inui 

 and the Cynocephali. 



In the digastricus maxillae inferioris there 

 is, especially in the Inui and Cynocephali, a 

 reunion between the two anterior fascicles or 

 venires, by which the power of the muscle for 

 the abduction of the lower jaw must be 

 strongly augmented. The other muscles si- 

 tuated between the hyoid and the chin re- 

 semble in the Chimpanzee, those of man, but 

 in the other monkeys they show marks of a 

 lower organisation. According to the ob- 

 servations of E. Burdach and myself, the 

 hyo-thyreoideus and hyo-glossus are united in 

 one, in the Inui and the Cynocephali. 



In the infra-hyoidian muscles, the only dif- 

 ference from man is, that the intermediate 

 tendon of the omo-hyaideus, which exists in 

 the Chimpanzee as in man, disappears in the 

 Iimi and in the Cynocephali, and that in 

 these monkeys the inferior portions of the 

 sterno-hyoidei and sterno-thyroidci are united 

 together. In the latisdmus dorsi, an interesting 

 transition to the form of the other mammalia 

 is observed, even in the Chimpanzee, by a pro- 

 longation attached to the olecranon. It seems 

 connected with the power that must be per- 

 formed by this muscle, in the action of climb- 

 ing. According to my observations in various 

 animals, the insertion of this prolongation 

 differs according to the variety of movements, 

 performed by the anterior extremities. 



The rhomboideus of the Chimpanzee has the 

 same form and situation as in man, but in the 

 Inni and the Cynocephali it goes to the oc- 

 ciput, in which its insertion serves to sustain 



205 



the head, in the quadruped progressive motion 

 of these animals. 



In the Inui and in the Cynocephali, but 

 not in the Chimpanzee, there is a conformity 

 with the form of the large Carnivora, in the 

 existence of the acromio-trachelien (Cuv.), 

 acromio-basilaire (ViCQ D'AZYR), coming from 

 the transverse processes of the first cervical 

 vertebrae, and inserted into the spine of the 

 scapula. Its function seems to be to bring 

 the scapula more strongly forwards. 



The pectoralis magnus, p. brevis, subclavius, 

 and serratus anticus magnus of the Chimpanzee, 

 the Orang-aetan,ax\d the Gibbons, resemble those 

 of man. The only difference is that, accord- 

 ing to the observations of SANDIFORT, thepec- 

 toralis magnus is divided in the adult Orang- 

 cetan into a large number of fascicles, in the 

 intervals of which are situated the digitiform 

 prolongations of the enormous laryngeal 

 pouch. But in the Mandrill the pectoralis 

 magnus acquires more analogy with the large 

 quadrupeds, by its greater extension, and its 

 separation into three great fascicles, of which 

 one comes from the posterior part of the 

 thorax. In the muscles of the anterior ex- 

 tremities the general distribution and form 

 are the same as in man. An interesting de- 

 viation is given by the Hylobates leuciscus, in 

 which the caput breve m. bidpitis takes origin, 

 from the insertion of the pectoralis magnus. 

 Can this peculiarity be connected with the 

 velocity of their movements, when they swing 

 themselves from one branch to another? Du- 

 VAUCEL affirms that they will on these occa- 

 sions leap, with comparative ease, to the 

 surprising distance of forty or fifty feet. About 

 the extensores of the fingers, a lower form may 

 be observed in the extensor digiti indicis, or 

 m. indicator, which is not a separate muscle, 

 but only a portion of the extensor communis. 

 Consequently the fore-finger, or index, must 

 want the so characteristic separate move- 

 ments, by which we are accustomed to call 

 the attention upon a subject. The imper- 

 fection of this muscle is certainly in relation 

 with the lower psychical condition of the 

 animal. In the Inui and the Mandrill the 

 extensores are still more imperfect, by the 

 division of the extensor digiti minimi, which 

 gives a tendinous insertion to the annular or 

 fourth finger. It is, as I showed in my work 

 upon the Chimpanzee, a transition to the form 

 of the Carnivora. The eight muscles of the 

 thumb exist in the Chimpanzee and in the 

 Hylobates leuciscus ; but in the Orang-cclan and 

 in the Mandrill the abductor longus and the 

 extensor brevis pollicis are united in their mus- 

 cular portions, while the tendons remain se- 

 parate, and in the Inui there is but one 

 muscle, giving two tendons, which are united 

 at their extremities. This is a distinct transi- 

 tion to the form of the Carnivora. I have 

 found this single muscle in all those -which 

 possess a thumb. The small muscles of the 

 thumb, viz. the abductor brevis, the Jlcxor 

 brevis, the adductor, and the opponcns, exist in 

 all the monkeys of the Old World, but on a 

 smaller scale than in man. They have also 



