xiv Journal of Comparative Neurology. 



a confused morphology has denied a name out of the plethora of cere- 

 bral nomenclature to be the exclusive property of this the dominant 

 organ of the nervous system and the master-structure of the whole 

 body ; for it has been linked with the hippocampus, which does not 

 share these high attributes, but has long since reached the height of its 

 importance, and is now on the wane in those mammals in which the 

 neopallium reaches its supreme development. A distinctive name — 

 corpus callosum — -is now very generally admitted for the commissural 

 fibers of this neopallium, in contradistinction to those of the hippocam- 

 pus — psalterium. Why, then, should not a like distinction be con- 

 ferred on the cortical areas from which the commissures ultimately 

 spring? . . . It must be obvious from the preceding discussion 

 that the terms 'rhinencephalon' and 'pallium' cannot be employed as 

 compliments the one to the other without considerable distortion of the 

 original meaning of one or both of the terms. 



"The pallium, in the strict sense, is composed of three distinct 

 structural elements : a ventral part, or pyriform lobe, the '■bastpalliu?n,' 

 the marginal pallium or hippocampus, and lastly that large dorsal cap, 

 the '■dorsipalUiim' or neopallium. If now we regard this term 'neopal- 

 lium' as the compliment of 'rhinencephalon/ it will involve a new defi- 

 nition of the latter which would then include the whole pyriform lobe, 

 the whole hippocampoil f':^rmation and paraterminal body, in addition 

 to the olfactory bulb, peduncle, and tubercle, and the locus perforatus. 

 Far from such an employment of the term proving awkward, it ex- 

 presses the obvious relationship of both the hippocampus and the pyri- 

 form 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. ... So far 

 as I understand the question at issue, there are two, and only two, 

 alternative meanings logically open to us for adoption. It [rhinen- 

 cephalon] may be employed to designate the olfactory bulb and pedun- 

 cle as Owen used it, and as such is unnecessary, and therefore super- 

 fluous ; or it may be used to include all those regions which are pre- 

 eminently olfactory in function, and have become definitely specialized 

 in structure in consequence. Such a definition will include the olfactory 

 bulb, its peduncle, the tuberculum olfactorium and locus perforatus, 

 the pyriform lobe, the paraterminal body, and the whole hippocampal 

 formation." c. j. h. 



