AND AFFINITIES OF THE GORILLA. 271 
coextensive backward with the cerebellum, and the beginning of the structures’ 
characteristic of the posterior lobes in Man are determinable. But, for the present 
zoological application, the following accurate definition by Tiedemann of the Human 
condition of some of these structures may be relied upon:—‘‘ Pedes hippocampi 
minores vel ungues, vel calcaria avis, que a posteriore corporis callosi tanquam processus 
duo medullares proficiscuntur, inque fundo cornu posterioris plicas graciles et retroflexas 
formant, in cerebro Simiarum desunt; nec in cerebro aliorum a me examinatorum 
mammalium occurrunt ; Homini ergo proprii sunt.” (‘ Icones cerebri Simiarum,’ p. 51.) 
With regard to other characters, if the naturalist, seeking the true cerebral endowments 
of the genus Homo, were to abandon his proper guide, viz. the average condition of the 
brain in the male sex, and to take the brain of a female of the lowest Papuan or Ethio- 
pian variety, he would nevertheless find that the primary cerebral convolutions charac- 
teristic of Man, and widely differentiating his brain, by their number, size, depth, and 
course, from the Ape’s brain, are all present, though they may be marked by fewer 
secondary fissures*. The cerebrum not only overlaps, but extends beyond the cere- 
bellum ; and the difference in the proportion of the cerebrum to the cerebral nerves, to 
the pyramidal bodies, to the bigeminal bodies, to the myelon, is such as to manifest as 
abrupt a step in development as that which is met with between the Lyencephalous 
and Lissencephalous types, or between the Lissencephala and Gyrencephala. The extent 
of difference in the proportion of the cerebrum to the above-cited parts in the different 
varieties of mankind is small, and with such slight gradational steps as to mark the 
unity of the family in a striking manner. I therefore conclude that the Human 
characteristics of the brain afford a zoological character of higher degree and importance 
than do those of his limbs, and concur in the functional estimate with which Tiedemann 
terminates his paper on the brain of the Orang :—‘‘ The cerebral hemispheres are thus 
most clearly shown to be essentially the instruments by which, in life, the intellectual 
functions are performed, since through the large size, circumferential expanse, and 
elaboration of the cerebrum Man differs from all other animals®.”’ It would seem, 
moreover, that the numbers of the Archencephala, under their manifold varieties, would 
* « Anfang des hintern, dritten Horns des Seitenventrikels’’ (Kuhl, in A¢eles, loc. cit.). ‘ Scrobiculus parvus 
loco cornu posterioris” (Tiedemann, in Macacus, ‘ Icones cerebri Simiarum,’ fol. p. 14, fig. iii. 2). ‘* Die grossen 
seitlichen Hirnhohlen bestanden aus dreien Hoérnern, einem yorderen, mittleren oder absteigenden, und einem 
hinteren Horn” (Tiedemann, on the Orang ; who is, however, silent as to any “hippocampus minor”’). It exists, 
however, in the condition described by Vrolik, as “une éminence que nous croyons ayoir le droit de nommer 
un indice de pes hippocampi minor” (“ Note sur l’encéphale de |’Orang,” in Versl. en meded. afd. natuurk. 
Deel xiii., 1861). 
2 The “primary” and “secondary”? convolutions and fissures are defined and distinguished in my paper on the 
Cheetah (Sept. 1833, Zool. Trans. vol. i. p. 134). 
* «So wird dadurch auch evidenteste bewissen, dass die Hemisphiiren des grossen Hirns vorziiglich als die 
Werkstiitte zu betrachten sind, durch welche im Leben die intellectuellen Verrichtungen vermittelt werden, 
dem eben durch Grésse, Umfang und Aussbildung des grossen Hirns unterscheidet sich der Mensch von allen 
iibrigen Thieren”’ (loc. cit. p. 28). This remark antagonizes that of Buffon, who, in regard to the Orang and 
