134 MAN AND TEE LOWER ANIMALS n 



eminence is what has been termed the " Hippo- 

 campus minor ;" the " Hippocampus major " being 

 a larger eminence in the floor of the descending 

 cornu. What may be the functional importance 

 of either of these structures we know not. 



As if to demonstrate, by a striking example, the 

 impossibility of erecting any cerebral barrier be- 

 tween man and the apes, Nature has provided us, 

 in the latter animals, with an almost complete 

 series of gradations from brains little higher than 

 that of a Rodent, to brains little lower than that 

 of Man. 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 man-like 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 cere- 

 bellum partially visible from above, and its poste- 

 rior lobe, with the contained posterior cornu and 

 hippocampus minor, more or less rudimentary. 

 Every Marmoset, American monkey, old world 

 monkey, Baboon, or Man-like ape, on the contrary, 

 has its cerebellum entirely hidden, posteriorly, 

 by the cerebral lobes, and possesses a large pos- 

 terior cornu, with a well-developed hippocampus 

 minor. 



