CONTRIBUTIONS TO THE MORPHOLOGY OF 

 THE BRAIN OF BONY FISHES. 



II.— STUDIES ON THE BRAINS OF SOME AMERICAN 



FRESH-WATER FISHES. — Continued. 



With Plates XXIV and XXV. 



C. L. Herrick. 



B. — Histology of the Rhinencephalon and Prosen- 

 cephalon. 



The following observations are restricted primarily to the 

 brain of the drum, Haploidonotus grimnicns ^ although also 

 based on a study of a large series of native fishes. 



In vievv^ of the novelty of many of the vievv^s presented, it 

 should be said that great pains has been taken to verify each 

 point, while our sections are so perfect as to make determina- 

 tion unusually easy. Nevertheless, in tracing unmedullated 

 fibres like those of the callosum and hippocampal commis- 

 sures., considerable uncertainty may exist respecting definite 

 connections. Such success as we have had in a satisfactory 

 settlement of a number of the vexed questions of the fish 

 cerebrum may be ascribed to improved technique and con- 

 stant reference to compai'ative data. 



The cerebrum and its related structures in fishes have so 

 long baffled investigation largely because of the failure to 

 recognize the morphological equivalent of the cortex and a 

 consequent misinterpretation of the cnelia. The only hope of 

 correcting this error lay in the strict and philosophical appli- 



