52 DISTINCTIVE CHARACTERISTICS OF MAN. 



prolongation attached to the olecranou, which is found in the lower Mam- 

 malia, and which exists even in the Chimpanzee, probably giving assistance 

 in its climbing operations. The larger size of the muscles of the thumb, is, 

 as might be expected, characteristic of the hand of Man ; although the num- 

 ber of muscles by which that digit is moved, is the same in the Chimpanzee 

 as in the Human subject. The separation of the " extensor digiti iudicis," 

 however, as a distinct muscle, is peculiar to Man. 



34. The Visceral apparatus of Man presents very few characteristic pecu- 

 liarities, by which it can be distinguished from that of the higher Quadru- 

 rnana; among the most remarkable is the absence of the laryngeal pouches, 

 which exist even in the Chimpanzee and Orang-outang, as dilatations of the 

 laryugeal ventricles. Of the anatomy of the last-named animals in their 

 adult condition, however, we know as yet too little to enable its conformity 

 to that of Man to be confidently pronounced upon. 



35. The Brain of Man does not differ so much in conformation from that 

 of the Chimpanzee and in this respect still more highly developed Orang, 

 as the superiority of his mental endowments might have led us to antcipate. 

 The following are the principal differences which it seems to present : 1. The 

 mass of the entire brain is considerably larger in proportion to that of the 

 body, and in proportion also to the diameter of the spinal cord and of the 

 nerves which are connected with it. 2. In the external configuration of the 

 Cerebrum, we notice that its anterior lobes are larger, project further beyond 

 the Rhinencephalou, or Olfactive Ganglion, than they do in the highest 

 Quadrumana; a difference which is well marked in the sectional contour of 

 the brain-case, the rhinencephalic fossa of the Oraug (Fig. 4, rJi) being at 

 its most anterior part ; whilst even in the least elevated forms of the Human 

 skull, this fossa (of which the cribriform plate of the ethmoid bone consti- 

 tutes the floor) has no inconsiderable part of the cranial cavity in front of it 

 (Fig. 6, rh). 3. The Cerebrum as a whole projects further beyond the Cere- 

 bellum than in the Quadrumana generally, which is clue not to any increase 

 in size of the occipital Convolutions, but to the great development of the 

 "bridging convolutions" interposed between the parietal and occipital 

 lobes. 4. The Convolutions are more numerous and complex, and usually 

 more or less unsymmetrical, and the sulci are deeper. It appears, however, 

 that in the lower races of Mankind, the brain presents, both in the simplicity 

 and the precise symmetry of its convolutions, a much closer approximation 

 to the Quadrumanous type than it does in the higher. 5. On examining the 

 internal structure it is found that the peripheral layer of gray matter is 

 thicker, the corpus callosum extends further backwards, and the posterior 

 cornua of the lateral ventricles are relatively longer and larger than they 

 usually are in Quadrumana. 1 6. The Cerebellum, also, is proportionally 

 larger. The relative development of the Cerebrum in Man and the three 

 highest apes is well shown in the accompanying drawings (Figs. 10, 11, 12). 



36. The small size of the face of Man, compared with that of the cranium, 



1 It has been asserted by Prof. Owen (Journal of the Proceedings of the Liniu'can 

 Society, vol. ii, p. 19) that the existence of the posterior lobes of the Cerebrum, of the 

 posterior cornua of the lateral ventricles, and of the hippocampus minor, which projects 

 into each cornu, is peculiar to the genus Homo. How strangely inconsistent is this 

 assertion with the well-known and certainly ascertained facts of the case, lias been 

 conclusively shown by Prof. Huxley in his Memoir "On the Zoological Relations of 

 Man with the Lower Animals, "in the Natural History Review, January, 1801, p. 71 

 et seq. ; and the chief points of the controversy have since been succinctly stated in 

 his Evidence as to Man's Place in Nature, 1803. For an excellent description of the 

 Convolutions of the Human Cerebrum, see W. Turner, Edin. Med. Jour., June, 1866, 

 and Ecker. 



