Kappers, Teleostean and Selachian Brain, 25 



medial bilateral elevations in the floor of the optic ventricle (in 

 this case the more caudal part of it). He also denied that optic 

 fibers are contained within it. Moreover Bellonci described 

 as fibrae ansulatae a crossing of disperse heavily medullated fibers 

 situated above his com. inferior, which he saw to end under the 

 roof of the lobi optici. Edinger, who does not describe the tele- 

 osts in his "Zwischenhirn," mentions in his "Vorlesungen" a 

 decussatio supra-optica ventralis and dorsalis and a commissura 

 ansulata and further mentions for the teleosts also a decussatio 

 tuberis, the latter as a connection between the ganglia anteriora 

 thalami of both sides. Of the first decussation he says that it 

 extends between the end of the caudal mid-brain and thalamus 

 ganglia, while the second would have a similar course (at least in 

 reptiles and birds) and the third (mentioned by him only for the 

 reptiles) perhaps is connected with the fasc. longitudinalis dorsalis. 



C. L. Herrick, who, as I have seen by my own investigations, 

 describes the 'tween-brain excellently, divides the com. transversa 

 of authors (com. inf., dec. supra-optica ventralis) into two fiber 

 groups, the lower one of which he calls com. ventralis, the upper 

 com. transversa. He considers them to be morphologically one, 

 as shown by their relation to the opticus system, and by the fact 

 that he finds that both end partly in the corpus geniculatum 

 laterale and partly farther backward in his colliculus (the torus 

 semicircularis of most investigators). Now, I agree in con- 

 sidering his first two commissures as one and add that he mentions 

 a second commissure of this praeinfundibular region, the com- 

 missura minor, a small compact system of fibers crossing directly 

 under the ventriculus tertius and ending where the opticus passes 

 into the tectum (as Edinger also represents the decussatio supra- 

 optica dorsalis of Gobio fluviatilis). 



In this area Catois also distinguishes two commissural systems, 

 of which, however, according to his opinion, the first connects the 

 corpora ecto-mammillaria as com. post-chiasmatica (which 

 Goldstein confirms) and the other is the com. transversa of 

 authors of whose fibers a small part ends in a separate group of 

 cells (probably my nucleus prasrotundus) situated before and 

 lateral to the nucleus rotundus, while the greater part ends in the 

 tectum opticum itself. Finally I must mention that Krause 

 finds the com. transversa ending in the stratum zonale of the tori 

 semicirculares and that by experimental investigation he definitely 



