Herrick, Morphology of Jyrain of Bony Pishes. 3c; i 



surate development of cranial walls forming a direct support 

 for the cortex has resulted in the gradual limitation of the 

 nervous matter within the axial lobe leaving only the pal- 

 lium to represent its former position; that the cell structures 

 proper to the cortex are contained in the axial lobe, which 

 is, accordingly, more complex than that of any other group 

 of vertebrates; that the two types of aesthesodic and kinesodic 

 cells are as distinct in fishes as in reptiles; that these cells are 

 grouped in distinct areas and may be classified into minor 

 divisions, based on size, etc.; and that the commissures and 

 tracts sustain much the same relations to these clusters that 

 they would if the latter lay in a cortex cerebri instead of the 

 axial lobe. Of the above conclusions, the suggestion as to 

 the cause of the suppression of the cortex is a mere guess, 

 incapable of serious attempt at demonstration; the others 

 seem to me well supported by the facts at hand. It is ob- 

 vious that one result of this peculiar limitation of the cortex 

 is to largely interfere with a free and generous development 

 ot the organs of consciousness and spontaneity. A fish 

 would be handicapped in any competition with animals 

 whose cortex would permit of easy increase by centrifugal 

 growth or by infolding and plications. 



In a preceding article it was shown that the axial lobe of 

 fishes is marked by deep and more or less constant fissures 

 separating topographically several lobes or areas. It remains 

 to show that each of these lobes has its own peculiar cell 

 structure and fibre connections, warranting the assertion 

 above made, that the axial lobe of a fish is more complex 

 than that of other animals, not even excepting the bird. 

 Before passing to the special description, reference is made 

 to the useful paper by Edinger, in which a great deal of 

 useful comparative matter is collected and discussed in the 

 light of recent literature.( ') The statement on page io6, 

 that " the amphibian brain is the simplest brain which is 



I Edinger, Dr. L , " Untersuchungen iiber die Vergleichende Anatomic des 

 Gehirns," I.; " Das Vorderhirn," Abhandl. Senkenbergischen naturf. Gesellbchaft, 1888. 



