Kappers, Teleostean mid Selachian Brain. 3 1 



1. Fibrce ansulatce. I have already called attention to the 

 fact that these fibers have been described by Bellonci as thick, 

 not very compact, but strongly medullated fibers, as they also 

 appear in my own preparations (Figs, xxxvi, xxxvii, Plate II). 

 He is of the opinion that they join the com. transversa and he was 

 able to follow their course as far as under the lobus opticus. As 

 it is very difficult to follow the course of these diffuse fibers between 

 which the median opticus bundle is also placed, I have nothing to 

 add about them save that they either end in the corpus genicula- 

 tum or running through this enter the anterior part of the nucleus 

 corticalis. In front they disappear in the commissura trans- 

 versa, from which perhaps they originate. That they should have 

 anything to do with the fasc. longitudinalis posterior, as Edinger 

 supposes for the reptiles, I can positively contradict as far as the 

 teleosts are concerned. 



2. The commissura tuberis is a thin bundle of fibers, very poor 

 in myelin (Fig. xxxviii) which unites the two halves of the tuber 

 cinereum and begins at the same place where the tractus praethal- 

 amo-cinereus (which was treated of in connection with the prae- 

 thalamus) terminates. 



3. Over the commissura tuberis we find the commissura 

 horizontalis of Fritsch strongly developed and easily followed. 

 Its point of decussation, is placed at the same place by all authors 

 (Fritsch, Mayser, Bellonci, Edinger, Herrick and Catois), 

 dorsad of the com. tuberis, caudad of the com. transversa. Bel- 

 lonci and Catois confirm the original description of Fritsch 

 that this commissure ends in the nuclei rotundi thalami, but 

 Mayser supposed that it only passed through these nuclei. 

 Edinger also says that the fibers which he marks as traversing 

 the nuclei rotundi in Gobio fluviatilis originate from the tectum, 

 while Herrick remarks, that they appear again as a compact 

 bundle above this nucleus, which he calls nucleus ruber, and ter- 

 minate in the nucleus corticalis, just as David describes. 



I can almost entirely confirm the statement of the last four 

 authors that the bundle comes out of the upper side of the nucleus 

 rotundus proprius as compact as it entered it at the lower side 

 (Fig. xlviii, Plate HI). Then it runs dorsad and joins two other 

 tracts, with which it then runs frontad under the optic ventricle 

 and in the same region with which it ends. This is the region of 

 the nucleus lentiformis, situated mesad of the nucleus corticalis 



