ST. HILAIRE ON THB SYSTEMATIC POSITION OF MAN. 7 



ciens) which, in their turn, are similarly superior to the rest. There is an almost 

 continuous series of modifications, of degradations, which are the more diverse, as they 

 are far from always affecting to a similar degree the development of the anterior lobe, 

 and that of the corpus callosum, or the condition of the convolutions. It may and 

 does happen, that these remain very numerous in a cerebram with its anterior lobes 

 and corpus callosmii more or less reduced; or, on the other hand, they may be more 

 or less obsolete in a brain which is still remarkable for its general development, for 

 the extent of its corpus callosum, and the volume of its anterior lobes. This last 

 combination is that presented by many apes of the third tribe (Cebiens), especially, 

 and more than by any other genus of the same group, by the Saimiris, which are 

 so remarkable for the richness of their cerebral development. The same combina- 

 tion is found, but carried to a still greater excess, in all the apes of the fourth tribe 

 (Hapaliens). In the Marmosets the brain is, at the same time, greatly developed as 

 a whole (less however than ui the Saimiris) and is devoid of convolutions ; it is 

 one of the richest brains in one direction, one of the poorest in the other. 



" These tacts have not yet been reduced to a law, either for the whole brain, or for 

 the corpus callosum, or for the anterior lobes ; but their connexion is easily appre- 

 hended, so far as the convolutions are concerned. If for the too complex comparison 

 of generic diiFerences, we substitute that of the general differences between one 

 tribe and another, the following is the immediate result : — In Man, the convolutions 

 are very numerous and are separated by deep sulci; in the first tribe (Suniens) 

 they are less numerous than in Man, more numerous than in the second; in the 

 second tribe (Cyn'opitheciens) they are more mmierous than in the third (Cebiens) ; 

 in which the cerebral gyri become more and more scanty, from the Ateles and the Cehi 

 to the Saimiris and the"Callitriches; exhibiting a gradual progress towards the fom-th 

 tribe (Hapaliens) which is distinctly characterized by the smoothness of the brain. 



" There is, then, a decrease in the convolutions in a serial order, from Man to the 

 first, second, third, and fourth tribes ; which in this point of view constitute five terms 

 of one and the same very regular series, from tlie maximum of the development of the 

 convolutions observed in Man, to their complete disappearance in the Marmosets — 

 and this series ends at the exact point, where the family of the Lemurida; succeeds to 

 that of the Apes ; a distinct series in which we see (in a brain in other respects 

 veiy differently constructed), the convolutions re-appear at the upper end of the 

 scale, in the ludri and the Lemurs, to disappear anew, at the lower end, in 

 Microcebus, 



" Whence flows this consequence, that may and will be better defined, but will 

 not be rendered more certain by future investigations: In any classification based 

 on the constitution of the brain and particularly on the condition of the convo- 

 lutions, two general divisions must be established among the Primates, one for man 

 and all the apes, the other for the Lemuridse ; and in the former two sub-divisions: 

 man and the apes with convolntions ; then the apes with smooth brains. 



" In other words, man is, in this respect, much nearer the higher Apes, than these 

 are, not merely to the Lemurs, but even to the lower types of their own family." 



After tliis clear and, upon the whole, just statement of the 

 cerebral relations of man to the apes, M. St. Hilaire takes up the 

 question of the facial angle. This angle, measured by the method of 

 Greoftroy and Cuvier, he affirms to become as small as 64° in a 

 South African people, the Makoias ; which is 6° less than the limit 

 ordinarily assigned to it in the human species. But in the adult 

 Saimiri the facial angle measured in the same way amounts, he affirms, 

 to 65°, and is but a few degrees less in the Gribbons and the Sem- 

 i2o/ji^Aeci, among the old world apes; in Cebus, Ateles, Eriodes, Lago- 

 thrix, Callithrix and Nyctipithecus among the apes ofthe new world. 

 After which, says M. St. Hilaire : — 



" It descends to about 50" in the Cercopitheci (a few degrees more or less according 



