Kappers, Teleostean and Selachian Brain. 55 



com. transversa enters into the anterior part of the subventricular 

 gray substance, stratum zonale tori semicircularis, a very incorrect 

 name which should not be used any more, as the torus semicircu- 

 laris (or semilunaris) is not yet found there but lies farther back- 

 w^ard and more dorsally. The slight medial vaulting of the ven- 

 tricular floor, which lies anterior to and more medial than the 

 torus semicircularis I shall hereafter always call eminentia medi- 

 alis. Under the stratum zonale of the eminentia medialis the 

 commissura transversa enters, which is in no way connected with 

 the torus semicircularis. In the lateral part of the eminence 

 mentioned where it borders on the tectum Fritsch found the 

 nucleus corticalis (in which the com. transversa ends for the 

 greater part), a very unfortunate name which, how^ever, has been 

 accepted by most authors. It indicates an imperfectly defined 

 group of cells which immediately passes over into another flatter, 

 more medial cell-layer of the eminentia medialis which has been 

 described as nucleus lentijormis mesencephali. Both cell-layers 

 together are indicated by Auerbach by the name "basal gray 

 substance" and by Goldstein as "nucleus dorsalis." I should 

 like to see the name torus semicircularis for the part posterior and 

 lateral to this given up and replaced by the name "colliculus" 

 given by Rabl Ruckhard and C. L. Herrick. This colliculus 

 is a definite well-defined cell-mass of which I shall speak further 

 in connection with the fasciculus longitudinalis lateralis and which 

 I consider the homologue or pro-stadium of the corpus quadri- 

 geminum posterius of higher vertebrates. 



Now I shall continue the description of those fibrae profundae 

 tecti that do not form part of the lamina commissuralis or the 

 commissura posterior. These, the lemniscus fibers, gradually 

 gather from all the remaining regions of the stratum profundum, 

 forming a lateral bundle situated between the brachium laterale 

 tecti and the stratum zonale eminentiae medialis (Fig. xliv, not 

 numbered). These are the most frontal lemniscus fibers which 

 consequently remain most lateral during their entire course in the 

 mid-brain and do not form part of the com. ansulata. None of 

 the most frontal fibers of the lemniscus decussate, in which I agree 

 with Edinger who gives excellent descriptions of these features. 



The next following fiber group is the first decussating group 

 (Figs, xlviii, il). In order to reach its lateral situation it has to 

 pierce through the colliculus; it also sends fibers to and receives 



