187 
into nuclet caudatus (figs. 4, 5, n.c.) and lenticularis (n.l.) by an 
imperfect internal capsule (t.c.). The internal capsule consists of 
a number of scattered bundles of fibres, which, however, form a 
more definite tract than the scattered fibre-system in Platypus, 
in spite of the larger pallium in the Monotreme. 
Fispre TRACTS IN THE CEREBRUM. 
Tt will not be necessasy to do more than mention the general 
arrangement of the fibres, since it does not differ to any extent 
from that found in other non-placental Mammals, the disposition 
of whose cerebral tracts I have described in greater detail else- 
where (37). The corona radiata (c.7.) forms the deepest layer of 
the cortex cerebri, forming the lateral wall of the lateral ven- 
tricle above and an external capsule below, separating the corpus 
striatum from the cortex (fig. 5). No centrum semi-ovale can be 
said to exist. Above the ventricle the corona becomes very thin, 
and terminates in the region of the subiculum cornu Ammonis, 
where its fibres mingle with those of the alveus. Below, a very 
considerable proportion of its fibres cross the middle line in the 
Jamina terminalis, forming part of the anterior commissure. The 
anterior commissure connects the corpora striata, ‘ pallia,” 
pyriform lobes (including nuclei amygdalz), tubercula olfactoria, 
and olfactory bulbs (probably only the prosencephalic part and 
peduncle). The pars olfactoria of the anterior commissure con- 
sists of a very large compact bundle (fig. 11), which takes a 
sudden bend forwards in the corpus striatum, and, passing through 
the olfactory peduncle on the outer side of the ventricle, radiates 
into all parts of the olfactory bulb, closely intermingled with the 
fibres of the olfactory radiations. 
There is no justification for dividing the rest of the commissure 
into pars frontalis and temporalis (Flower, Osborn). The great 
bulk of the anterior commissure corresponds to Koelliker’s pars 
posterior (15), which runs in the external capsule. In considering 
this part of the commissure in Marsupials it must always be re- 
membered that a considerable proportion of these fibres represent 
the corpus callosum of Eutheria, and therefore cannot be com- 
pared to any part of the anterior commissure proper. 
The fornix system in Wotoryctes, as in all Marsupials, exhibits 
an extreme simplicity, and is not divided up into fornix obliquus 
or f. longus of Forel, nor is the stria Lancisi separated from the 
rest of the fornix fibres. 
It will suffice to give here little more than a list of the olfac- 
tory tracts, elucidated mainly by comparison with Perameles. 
a. The external olfactory radiation (Edinger) arising in the 
olfactory bulb and terminating upon the surface of the 
pyriform lobe and tuberculum olfactorium. 
