Kappers, Teleostean and Selachian Brain. ' loi 



bundle of Stieda and upon closer examination can be distin- 

 guished from them easily. 



The posterior motor root of the vagus nerve was already con- 

 sidered as A^. accessorius by Claus and Rohon, which was duly 

 proved by Furbringer, who stated that in Hexanchus it inner- 

 vates the m. trapezius. Haller and Edinger both consider 

 this to be true. This root originates in the same way as the other 

 motor vagus roots (Fig. cvii) and from a continuation of their 

 nucleus. 



CONCLUSIONS. 



From the course of the secondary olfactory tracts, the tertiary 

 bilateral connections of the secondary olfactory centers and the 

 tertiary caudal connections of these centers it results that the lobi 

 anteriores of the teleosts contain regions which in the selachians 

 are situated in the pallium. 



Only a part of the median tract joins the tractus strio-thal- 

 amicus in the selachians; another part ends in the ventral region of 

 the fore-brain, so constituting a dorso-ventral connection in the 

 prosencephalon. 



The nucleus magnocellularis praeopticus of the teleosts has a 

 connection with the tuber cinereum. 



The commissure of Herrick ends in the same layer of the tec- 

 tum opticum as the optic fibers themselves. 



The centripetal optic fibers, the fibrae tectales nervi optici and 

 the brachia tecti have been correctly described by Krause. His 

 doubt, however, regarding the fasciculi mediales nervi optici has 

 no ground. These are optic fibers which join the commissure of 

 Herrick and end in the superficial layers of the tectum. 



The saccus vasculosus is a sense organ. 



The colliculi (tori semicirculares) of the bony fishes may be 

 considered as a prostadium of the corpora quadrigemina posteri- 

 ora of higher vertebrates. 



The posterior commissure contains no direct fibers for the 

 fasciculus longitudinalis posterior. 



The difference of opinion about the thalamic or mesencephalic 

 origin of this tract is due to the presence of a thalamic fiber system 

 which joins the mesencephalic system and which, by some authors, 

 evidently has been regarded as constituting a part of the fasciculus 

 longitudinalis posterior. Since, however, the thalamic system 



