230 THE DESCENT OF MAN. 



copithecu*, Macacus, Cebus, Callithrix, Lemur, Stenops, Ilapale, we 

 shall not meet with a greater, or even as great, a break in the degree 

 of development of the convolutions as we find between the brain of 

 a man and that of an orang or chimpanzee." 



To which I reply, firstly, that whether this assertion be true or 

 false, it has nothing whatever to do with the proposition enunciated 

 in "Man's Place in Nature," which refers not to the development of 

 the convolutions alone, but to the structure of the whole brain. If 

 Prof. Bischoff had taken the trouble to refer to p. 96 of the work he 

 criticises, in fact, he would have found the following passage: " And 

 it is a remarkable circumstance that though, so far as our present 

 knowledge extends, there is one true structural break in the series of 

 forms of Simian brains, this hiatus does not lie between man and the 

 manlike apes, but between the lower and the lowest Simians, or in 

 other words, between the Old and New World apes and monkeys and 

 the Lemurs. Every Lemur which has yet been examined, in fact, 

 has its cerebellum partially visible from above; and its posterior lobe, 

 with the contained posterior cornu and hippocampus minor, more or 

 less rudimentary. Every marmoset, American monkey, Old World 

 monkey, baboon, or manlike ape, on the contrary, has its cerebellum 

 entirely hidden, posteriorly, by the cerebral lobes, and possesses a 

 large posterior cornu with a well-developed hippocampus minor." 



This statement was a strictly accurate account of what was known 

 when it was made; and it does not appear to me to be more than 

 apparently weakened by the subsequent dis.covery of the relatively 

 small development of the posterior lobes in the Siamang and in the 

 Howling monkey. Notwithstanding the exceptional brevity of the 

 posterior lobes in these two species, no one will pretend that their 

 brains in the slightest degree approach those of the Lemurs. And 

 if, instead of putting Hapale out of its natural place, as Prof, Bischoff 

 most unaccountably does, we write the series of animals he has 

 chosen to mention as follows : Homo, Pithecus, Troglodytes, Hylo- 

 bates, Semnopithecus, Cynocephalus, Cercopithecus, Macacus, Cebus, 

 Callithrix, Hapale, Lemur, Stenops. I venture to reaffirm that the 

 great break in this series lies between Hapale and Lemur, and that 

 this break is considerably greater than that between any other two 

 terms of that series. Prof. Bischoff ignores the fact that long before 

 he wrote Gratiolet had suggested the separation of the Lemurs from 

 the other Primates on the very ground of the difference in their cere- 

 bral characters ; and that Prof. Flower had made the following 

 observations in the course of his description of the brain of the Javan 

 Loris : * 



"And it is especially remarkable that, in the development of the 

 posterior lobes, there is no approximation to the Lemurine, short- 

 hemisphered brain, in those monkeys which are commonly supposed 

 to approach this family in other res'pects, viz., the lower members of 

 the Platyrrhine group." 



So far as the structure of the adult brain is concerned, then, the 

 very considerable additions to our knowledge, which have been made 

 by the researches of so many investigators during the past ten years 

 fully justify the statement which I made in 1863. But it has been 



* " Transactions of the Zoological Society,-"" yol, y, 1868. 



