OLFACTORY CENTERS IN TELEOSTS 225 
that the fibers connected with the more rostral part of the basal 
lobes lie ventrally and medially; that those belonging to the mid- 
portion of each lobe hold an intermediate position, while the more 
caudal fibers appear dorsally in the praethalamic bundle. It 
will be noted, also, that those which decussate in the anterior 
commissure are among the more caudal fibers, while those of the 
extreme caudal tip of the basal lobes occupy the extreme dorsal 
position and form the lateral hypothalamic tracts (figs. 36, 37, 
55, 61, ‘68, 69,.72; 73). 
The lateral forebrain bundle receives from, or sends fibers to, 
all parts of the basal lobes excepting the corpus precommissurale, 
nucleus medianus, nucleus supracommissuralis, primordium hip- 
pocampi, and possibly the nucleus preopticus. The fibers from 
the caudal part of the lopes belong to the nucleus pyriformis 
chiefly, although a few fibers are undoubtedly in connection with 
the lateral part of the nucleus intermedius; they, therefore, form 
a tract corresponding to the tractus olfacto-hypothalamicus later- 
alis of Kappers. Kappers, however, described this as a descend- 
ing tract, while it here contains both ascending and descending 
fibers, which reach all parts of the nucleus pyriformis (figs. 69, 
Gene 
A large part of the fibers of the tractus strio-thalamicus, or 
remaining portion of the lateral forebrain bundle, are ascending 
and are distributed to all parts of the palaeostriatum, nucleus 
olfactorius lateralis, including the dorso-lateral area of the basal 
lobes, called epistriatum by Catois and by Johnston (’06). Many 
of these ascending fibers enter into relation with large association 
cells of these areas, their neurites enclosing the perikarya of the 
cells (figs. 49, 50,51). Other ascending fibers reach the peripheral 
area and branch dichotomously to form tangential fibers (fig. 39), 
here coming into relation with the association cells and their 
processes. Descending fibers of the tractus strio-thalamicus arise 
from cells found in all parts of the same areas, palaeostriatum, 
nucleus olfactorius lateralis, etc., already described. The nucleus 
olfactorius lateralis, and most, if not all of the palaeostriatum 
receive secondary olfactory fibers, while the palaeostriatum 
receives also processes from association cells of the corpus pre- 
THE JOURNAL OF COMPARATIVE NEUROLOGY, VOL. 22, NO. 3 
