210 RALPH EDWARD SHELDON 
basal lobes of the carp is similar, therefore, to its’ending in the 
majority of other teleosts; it has been possible, however, to dem- 
onstrate fibers from the tractus olfactorius lateralis in the dorsal 
and dorso-lateral region of the basal lobes, called by Johnston 
(06) the epistriatum. This area is, therefore, simply a part of 
the lateral olfactory area. 
(2) Tractus olfactorius medialis. The medial olfactory, de- 
scribed by the earlier workers as a single tract, and by the most 
recent as two, is really composed in the carp of five bundles of 
widely varying relationships (figs. 22, 23, 124, 186, 137). 
Tractus olfactorius ascendens. The tractus olfactorius ascen- 
dens described by Kappers, in Salmo, Gadus, ete. (radix olfactoria 
medialis propria) as a centripetal tract is, in the carp, as shown by 
Golgi preparations, a centrifugal bundle, originating from cells 
in the nucleus medianus (figs. 27 to 31). Catois described the 
more medial portion of the medial tract as centrifugal, but other 
authors have been unanimous in considering all excepting a few 
commissural fibers as centripetal. The fibers of the tractus 
olfactorius ascendens gather from all parts of the nucleus medianus 
and extend rostrad.to the bulb in two bundles which occupy the 
middle or intermediate portion of the base of each crus (figs. 24, 
23, 22). On reaching the olfactory bulb the fibers gradually 
spread out, and end in the nucleus olfactorius anterior (figs. 124, 
136). 
Tractus olfactorius medialis. Medially in the bulb and crus 
is found the tractus olfactorius medialis. This originates almost 
entirely from mitral cells and contains the neurites from practi- 
cally all the mitral cells far rostrally in the bulb; it may be traced 
much farther rostrally than any: of the other tracts of the crus. 
Throughout most of the bulb three bundles, belonging to this 
tract may be identified (for two of them see fig. 6); near the caudal 
margin of the bulb, however, these three join to form two, which 
may be traced separately to their termination in the basal lobes. 
The two lateral bundles originate almost entirely from cells at 
the extreme rostral end of the bulb, joining to form the tractus 
olfactorius medialis, pars lateralis. This can be distinguished 
from the tractus olfactorius medialis, pars medialis throughout 
