CONTRIBUTION TO THE MORPHOLOGY OF THE 

 BRAIN OF BONY FISHES. 



II. -STUDIES ON THE BRAIN OF SOME AMERICAN FRESH- 

 WATER FISHES.-Continued. With Plates IV-XII. 



C. L. Herrick. 



C. — HiSTOLOdV OF THE DiENCEPHALON AND MESENCEPHALON. 



The present instalment of this paper is based upon a con- 

 siderably increased material, including a number of series of 

 European fresh-water and marine forms, in many cases the same 

 species which have been used by the pioneers m this field. 

 Considerable embryological material has also become available 

 from which it is hoped to derive additional facts in a later instal- 

 ment. In consideration of the obligation imposed by the pos- 

 session of a variety of material probably never before available 

 for this purpose, the writer has endeavored to exercise all care 

 possible in the statements made. Considering the difficulty 

 attending this region and the fact that our ablest anatomists 

 differ ^fundamentally in such important matters as the origin of 

 the optic nerve, absolute accuracy is out of the question. It 

 appears unquestionable, however, that the brain of Teleosts is 

 the proper quarter in which to seek the solution of the very im- 

 portant problems respectmg the fibre paths in the mid-brain. It 

 is in this case simply a question of sufficiently numerous and 

 complete series, for one can trace fibres to cells in a way mipos- 

 sible elsewhere. Enough is indicated in this paper to prove 

 that in all essentials the fish brain is constructed on the same 

 plan as that of higher animals and, if the suggestion of mmute 

 homologies with mammalian organs seems audacious to those 

 who recall that living authorities are not agreed as to which part 

 of the brain represents the cerebrum and whether or not there 



