lO NERVE COMPONENTS OF BONY FISHES. 



and our knowledge of the exact relations in the fishes 

 is as yet very fragmentary. Nevertheless enough has 

 already been done to indicate the broad lines along 

 which these correlations are to be looked for and we may 

 now associate the several lobes of the medulla oblongata 

 which are so characteristic of the fishes with their respec- 

 tive cutaneous or visceral sense organs as definitely as the 

 olfactory nerves are associated with the olfactory lobes or 

 the electric lobes of the torpedo with the electric organs. 



J 



XL. 



Text-Figure i. 



Text-Figure i. — Brain and part of spinal cord of Prz'onotus seen 

 from above. After Morrill. The spinal nerves are numbered in 

 Arabic numerals. Cb. — cerebrum; cdl. — cerebellum; m. o. — medulla 

 oblongata; op. I. — optic lobes. 



Moreover the homologies of these lobes among the differ- 

 ent groups of fishes and in the higher vertebrates, even 

 up to the human brain, can now be followed with con- 

 siderable precision, as we shall see beyond. 



