283 THE BRAIN OF QUADRUMANA. 



and does not pertain to the brain in all Quadrumana ; it 

 exists only in some of the higher Monkeys and Apes. 

 It consists in the replacement of a single protuberance 

 (the * mammary ') existing at the base of the brain in 

 Quadrupeds by two smaller projections (' Corpora mamil- 

 laria ' or * albicantia '), side by side in the same situation, 

 each of which is produced by a bend of one of the ' an- 

 terior pillars ' of the Fornix (p. 273). 



(5.) A fifth character may also here be mentioned; 

 though this is likewise not common to the whole class. 

 Speaking of the Olfactory Lobes, Prof. Flower says : * 

 " In the large majority of mammals, the base of these lobes 

 extends backwards to the under surface of the temporal 

 lobe, obliterating the lower part of the fissure of Sylvius, 

 whereas in the true Apes and in Man, their connexion 

 with the Cerebral Hemisphere is chiefly with the anterior 

 lobes and the bottom of the fissure itself." 



The convolutional arrangement we have now to con- 

 sider is known as the 'Transverse Pattern/ No dis- 

 tinct transition forms are known between it and either of 

 the other two patterns, though Flower f seems inclined 

 to think that this may hereafter be found in Bats of larger 

 size than have hitherto been examined. In common 

 Bats the Cerebrum is very short and the Sylvian Fissure 

 almost non-existent. Among them, in fact, no species exists 

 of sufficient size to possess sulci on its surface. But this, 

 as Flower remarks, is not so very surprising "when such 

 markings are almost absent in the brain of a true Primate 

 of even larger size (Hapale)." For, in regard to convolu- 

 tional development, the same primary rule holds good 

 among Quadrumana as with Quadrupeds, viz., that, taking 



* " Trans, of Zoolog. Soc. 1866," vol. v. p. 108. 

 f Loc. cit., p. 109. 



