small nerve cells cliietlv in the cainial and upper part of the torus" 

 (op. cit., p. 342 — 343 and 348, without vet having applied to the 

 latter a special name (ganglion isthmi). 



molec. layer 



tt'ct. furrow 



liiiriznrJalis 

 fibre group 









Tr. islmo-tect. mihi 



Tr. ^eiikiilo-myttincerjli. HOLMGREN. 

 Cornrn. tratisv. 

 Tr. i.halamo-loh. 



Fig. 5. Clupea harengus. ' 



(Preparation of the Central Institute for Brain research. Amsterdam. 'i 



After Mayser no authors had occupied tlieinselves, as far as I 

 know, with this interesting tihre bundle, till F'r.asz discovered it 

 again. 



Tlirongh the result of this investigation the relation between the 

 tectum opticuni and the ganglion isthmi with Teleosts gets closer. 

 The connection i^ twofold, one tin)e through the tr. tecto-isth- 



niicus of Franz, another time through the 



isthmo-tectalis of 



myself, and we may presume that the first leads tectofngal, the 

 latter tectopetal. 



Although Mayskr's opinion that the bundle in question originates 

 from the corpus geniculatum externum s. 1. (i.e. from nucl. prae- 

 tectalis of the authors) cannot be confirmed by me as to the Cypri- 

 noids (s. above), yet I saw in a specimen of Exocoetus asmall[iart 

 of the fibres of my tr. isthmo-tectalis end in the nncl. praetectalis, 

 the other larger part running further frontad past this nucleus. The 

 .same 1 have been able to find with Cyclopterus, Trachinus, with 

 some doubt also with the Gasterosteids, Syngnathidae, Belone and 

 Solea. As just on the spot where these fibres should enter and end 



