Kappers, Teleostean and Selachian Brain. 1 7 



If the teleosts have a vestige of a nervous palHum, this certainly 

 is to be found in the place where C. L. Herrick sought it and 

 Studnicka supposed it to be, and in the selachians the bilateral 

 connection of that part might have come to lie in a more dorsal 

 position with the enormous development of the pallium. This 

 interpretation of the decussation is the more probable, as the com- 

 missura anterior itself, which in teleosts includes this commissure, 

 is poorly developed in Galeus and in Angelus squatina in com- 

 parison with their large olfactory centers; and it will appear still 

 more probable after I have described the caudal connections of 

 the secondary olfactory region of the sharks in comparison with 

 the tractus olfacto-hypothalamicus medialis and lateralis of the 

 teleosts. 



In the same dorso-lateral region in which the decussatio inter- 

 hemispherica originates there also arises a large medullated 

 bundle which Botazzi in his first publication calls fasciculus 

 cortico-medialis. This name he afterward altered to that which 

 Edinger had already given to the same tract, viz., median bundle, 

 and then applied the name fasc. cortico-medialis to a tract which 

 he had originally described as fasc. cortico-medialis centralis. 

 As I also prefer to retain the usual nomenclature, I name this 

 bundle as Edinger did. 



The median bundle has a fan-shaped origin of large extent in 

 the lateral sub-cortical layer and runs toward the median line over 

 that portion of the decussatio inter-hemispherica which has already 

 crossed and under the part of this decussation which has not yet 

 crossed, as clearly appears in Figs, xviii and xix, Plate I. Then it 

 runs obliquely downward between the two lateral ventricles to the 

 brain floor, where a portion of it again bends laterally, thus con- 

 stituting a connection between the superior and inferior parts of 

 the fore-brain, as Botazzi supposed, while another part of the 

 fibers joins the tractus strio-thalamicus with which they go to 

 the hypothalamus. This bundle does not decussate, either in the 

 decussatio inter-hemispherica or in the commissura anterior. 

 This can be stated positively; and, moreover, Botazzi himself, 

 who did not consider a decussation of some of its fibers impossible, 

 writes that he found it impossible to adduce much evidence for 

 this. 



Parallel with this bundle there is a second one, first described 

 by Botazzi, who called it, tractus cortico-medialis, or tractus 



