450 PEOFESSOK G. ELLIOT SMITH, 



the olfactory bulb, peduncle and tubercle, and the locus per- 

 foratus. Far from such an employment of the term proving 

 awkward, it expresses the obvious relationship of both the 

 hippocampus and the pyriform lobe to the olfactory apparatus 

 in so natural a manner as to afford the last convincing link in 

 the chain of evidence for this rational basis of division into 

 neopallium and rhinencephalon. 



It is a matter of common knowledge that the olfactory 

 peduncle passes into direct continuity with, and in addition 

 exhibits further most intimate links with, the paraterminal body 

 and hippocampus (mesially), and with the tuberculum olfacto- 

 rium and pyriform lobe (laterally). And there is ample proof 

 that all these parts of the brain are pre-eminently, if not wholly, 

 olfactory in function. In anosmatic animals {e.g., Phocmna) the 

 hippocampus dwindles, the paraterminal body almost com- 

 pletely vanishes, and the typical elements in the tuberculum 

 olfactorium and pyriform lobe practically disappear. All these 

 regions are, therefore, eminently worthy of the name " rhin- 

 encephalon." 



Ziehen ^ objects to this term, because the pyriform lobe does 

 not wholly vanish in anosmatic mammals, and he refers to the 

 superficially apparent paradox of a smell-less animal possessing a 

 " smell-brain " (rhinencephalon). One might with more justice 

 object to the term " optic thalamus " because the greater part of 

 this body persists in eyeless animals, or to the term " trigonum 

 acusticum" because the lateral regions of the floor of the fourth 

 ventricle still remain in deaf mammals ! But the fact that 

 other terms are not perfect is not a sufficient reason for retain- 

 ing the name " rhinencephalon " if a better can be found. Un- 

 fortunately this name is not new, and no amount of w^riting is 

 likely to rid the Science of Anatomy of the term, even if this 

 were desirable. And no one acquainted with recent literature 

 can pretend that the term has any precise meaning at present. 

 Therefore we should endeavour to attach to it the most natural 

 and useful meaning. 



So far as I understand the question at issue, there are two, 

 and only two, alternative meanings logically open to us for 



^ Das Cenlralnervensiistcm dcr Monolrcmen und Marsupialier, 1897, 

 p. 23. 



