OLFACTORY CENTERS IN TELEOSTS AA 
commissural fibers connecting the two nuclei teniarum, taking 
this course, and running in the tractus teniae (Edinger (’08) fig. 
231), as in the Amphibia. Such fibers would be comparable with 
the commissura pallii posterior (commissura aberrans) of lizards. 
Several different fiber systems arising from cells in the habenular 
ganglia have been described. As indicated above, Edinger, in 
his earlier work, believed that the tractus teniae arosein the haben- 
ulae, the tractus ad proencephalon. He also describes in sela- 
chians a tract to the midbrain roof, the tractus ganglia habenulae 
ad mesocephalon dorsalis; a tract to the midbrain base, the trac- 
tus descendens ganglii habenulae, in addition to the long known 
Meynert’s bundle, or fasciculus retroflexus, more recently de- 
scribed. by Goldstein, Edinger, etc. under the name ‘tractus haben- 
ulo-interpeduncularis.’ Beia Haller observed fibers arising in 
the habenulae and entering the optic apparatus, ‘Habenular- 
wurzel des Opticus;’ also a tract extending ventrad into the dien- 
cephalon, ‘Hauben-Zwischenhirnbahn.’ 
(2) Fasciculus retroflecus. The fasciculus retroflexus in the 
carp is a strong, chiefly unmedullated tract, originating partly 
from cells of the habenulae (fig. 75) and partly from the nucleus 
posthabenularis, as pointed out earlier by Bela Haller and Gold- 
stein (figs. 141, 142). From this point it extends caudad to the 
corpus interpedunculare, as described by practically all writers 
on the habenular connections (figs. 77, 79, 80, 82, 83, 100, 101, 102, 
114, 115, 116, 122). As noted by Goldstein, it is surrounded by 
medullated fibers caudally. These originate from the nucleus 
posthabenularis and pass caudad to the commissura ansulata, 
which they appear to enter, turning laterad. Goldstein simply 
figures these fibers, giving no description of their connections. 
(3) Tractus habenulo-diencephalicus. This tract arises in the 
habenulae and, descending into the more ventral diencephalic 
regions, 1s easily identified in the carp, as it is heavily myelinated. 
Haller traces it into the nucleus posthabenularis, while Gold- 
stein thinks that it ends farther ventrally, possibly in his nucleus 
dorsalis. The tract, according to the conditions in the carp, 
contains both ascending and descending fibers and extends ventro- 
caudad from the habenular ganglia practically to the nucleus. 
