Kingsbury, Oblongata in Fishes. 25 



third though small fusion of the lobi vagi. It is a difficult mat- 

 ter to represent by diagram the successive degrees of complex- 

 ity in the teleosts which lead up to the sucker {Catostomus) as 

 their climax. It has however been attempted in Figs. 30-33. 

 When other orders and families of teleosts are examined other 

 modifications and degrees of development will doubtless be 

 found to exist, and in other families of the orders represented 

 here ; while in other genera of the families, conditions may be 

 found which will bridge over the differences between the fami- 

 lies or orders, so that any generalization from the relations so 

 far found constant, is unsafe.^ The various developments of 

 the nerve centers are too clearly dependent on the extent and 

 functional activity of the regions or organs innervated to have 

 much morphological value attached to them. The cause of the 

 fusions that occur seems a difficult matter and no attempt has 

 been made to determine in how far the interference of the cra- 

 nium or ear during development may be responsible. Surely 

 however from such a form as Aniiiinis with widely separated 

 acusticums, it would be hard to derive a cyprinoid with fused 

 acusticums and lobi trigemini. 



Strong's work on the cranial nerves of Amphibia has been 

 previously mentioned as the direct inspirer of these obser- 

 vations and it seems to the writer a most helpful step toward 

 the comprehension of the cranial nerves of vertebrates in offer- 

 ing grounds for the homologization of the nerve roots through- 

 out the vertebrate series, and thereby the regions of the oblon- 

 gata with which they are associated ; and in the determination 

 of the components of the nerves, their origin and peripheral 

 distribution, to assist the facts of development in the solution 

 of the problems of the morphology of the vertebrate head and 



^ A careful study of the brain of the different orders and families of the 

 teleostei has never been made and seems to be a piece of work much needed, 

 Mayer undertook such a study of the teleost brain to make it the base of classi- 

 fication. His work was evidently superficial and his figures indefinite or in- 

 correct. The Herricks in this country have done much in the study of the 

 teleost brain. The bony fishes would certainly offers a good field for testing 

 the value of the brain in taxonymic work. The results so far gained suggest 

 that some interesting results may be gained. 



