208 



QUADRUMANA. 



3. The existence of two separate corpora 

 mammillaria, which I found also in the Hylo- 

 bates leuciscus, and which SANDIFORT repre- 

 sented in the Siamang. But they are in these 

 less developed than in the Orang-cetan. 



4. The presence of digitations on the cornu 

 Ammonis. 



5. More numerous convolutions and deeper 

 anfractuosities. 



6. A larger cerebellum. 



In all these peculiarities, the brain of the 

 Orang-cetan is superior to that of other mon- 

 keys, and still more so to that of the Gibbons, 

 which offer otherwise so much analogy with 

 it. The plate of SANDIFORT, representing the 

 brain of the Siamang, and my dissection of 

 the Hylobates leuciscus, have proved, that in 

 the Gibbons the convolutions are not so 

 numerous ; the anfractuosities not so deep, 

 their symmetry greater ; the cerebral hemi- 

 spheres less developed ; the cerebellum small- 

 er ; the pons VAROLII less distinct ; the cornu 

 Ammonis without digitations. This greater 

 perfection of the brain of the Orang-cetan is 

 evidently in accordance with the more eminent 

 intellectual faculties of the Orang-cetan, while, 

 according to the observations of DUVAUCEL 

 and of S. MULLER, the Siamang and the other 

 Gibbons are very stupid. But if, on one side, 

 this superiority of the brain of the Orang-cetan, 

 with which the Chimpanzee seems to have a 

 great deal of analogy, cannot be a subject of 

 controversy amongst anatomists, they would 

 however go too far by saying, that the brain 

 of both is in all points similar to that of 

 man. The following differences may be indi- 

 cated : 



1. The mass of the brain, in proportion to 

 the volume of the body, is less in these Apes 

 than in Man. 



2. The cerebral hemispheres are less deve- 

 loped, and not so much protracted backwards. 



3. The nerves are thicker in proportion to 

 the circumference of the brain. 



4. The convolutions are not so numerous, 

 and the anfractuosities less deep. 



5. The corpus callosum is not so much ex- 

 tended backwards. 



About the nerves of the Monkeys, T shall 

 but mention one very interesting modifi- 

 cation, which I observed in the nervus acces- 

 sorius WILIJSII of the Chimpanzee. It is 

 divided into two branches, as in man, but the 

 internal is not united with the vagus, as it 

 penetrates separately into the larynx. This 

 very peculiar ramification seems to confirm 

 the opinion of BISCHOFF *, that the internal 

 branch of the n. accessorius WILLISII forms 

 partly the n. laryngeus superior. About the 

 organs of sense there is not much to say. 

 The eye approaches much to the eye of the 

 human subject, by the existence of the yellow 

 spot on the retina, but it differs by a more 

 thin sclerotica. The ears of the higher order 

 of monkeys resemble much the same organs in 

 the human subject, from which they differ 



* L. W. T. Bischoff, Nervi accessor!! Willisii, 

 Anat. et Physiol. Darmstadii, 1832. 



only by a less developed lobulus. The tongue 

 is short, broad, and round, as in man, but it 

 becomes long and narrow in the Inui, and 

 still more so in the Cynocephali. 



ANGEIOLOGY. In the distribution of the 

 vessels and the form of the heart, the mon- 

 keys of the Old World offer a great analogy 

 with the disposition of the same parts in the 

 human subject. But few differences can be 

 mentioned. In the trunks arising from the 

 arcus aortce, the superior order of monkeys, as 

 the Chimpanzee and adult Orang-cetan, offer 

 the same number and distribution as in Man ; 

 but in the Semnopitheci, the Macaci, and Cy- 

 nocephali, there is a commencement of a de- 

 scending scale in the disposition of the A. 

 innominata, which divides into three branches, 

 viz.. the right subclavian and the two carotids, 

 in the same manner as in the Marsupials and 

 Carnivora. It is interesting, that I found also 

 this distribution in four young Orangs-cetan, 

 but that Sandifort observed in the adult 

 the human-like division. In the other ramifi- 

 cations, the resemblance to those of man is 

 very great. The plates of descriptive anatomy 

 which I published on the Chimpanzee, will be 

 sufficient to prove the truth of this assertion. 



SPLANCHNOLOGY. No parts of the ana- 

 tomy of the monkeys are, perhaps, more inter- 

 esting than the pouches of the larynx. I have 

 published a great number of observations 

 about them, by which is proved : 1. that they 

 exist in the Chimpanzee, the Orang-cetan, the 

 Siamang, the Semnopitheci, Cercopit/ieci, Inui, 

 and the Cynocephali ; 2. that they are larger in 

 the males than in the females; 3. that they 

 grow with the age of the animal, and are 

 consequently the largest in the most aged ; 

 4*. that they are chiefly a dilatation of the 

 laryngeal ventricles in the Chimpanzee and in 

 the Orang-cetan, but that in the other monkeys 

 they are in direct communication with the 

 cavity of the larynx, by an aperture at the basis 

 of the epiglottis ; 5. and that they are'wanting 

 in the Gibbons, the Cercopithecus radiatus, the 

 Cercopithecus mona and Cynocephalus porcarius. 

 It is very difficult to derive any physiological 

 conclusion from all these anatomical state- 

 ments. The most probable hypothesis seems 

 to be, that these receptacles of air, which 

 send their prolongations between all the mus- 

 cular fascicles {fig. 131), seem to diminish the 

 specific gravity of the body, in the action of 

 climbing, and that they are consequently 

 passive organs of movement. I have offered 

 this opinion in greater detail in my work upon 

 the Chimpanzee, and I refuted there the 

 opinion that they were connected with the 

 utterance of voice. The other parts of the 

 laryngeal apparatus do not differ much from 

 those of man, with the exception of the 

 hyoid bone, which has much of the human 

 form in the Chimpanzee, in the Orang-cetan, 

 and in the Gibbons, but the basis of which is 

 changed into a convex and elongated shield 

 in the other monkeys, in which the laryngeal 

 pouch opens below the epiglottis. 



In the form and structure of the heart and 

 the lungs, there is no difference between the 



