1527 JourNnaL oF ComPaARATIVE NEUROLOGY. 
nel, forming the JM/edianbiindel of EDINGER (’88) ; see Fig. 31, 
m. s.t. The median bundles, right and left, are thus carried 
posteriorly and ventrally beside the recessus neuroporicus 
toward the base of the brain. Here each blends with the part 
of the tractus strio-thalamicus taking origin from the striatum 
of that side, forming its central portion. 
The course taken by the median bundle, curving foward as 
it does to lie beside the vestige of the neuropore, is certainly 
fraught with significance. This is probably an ancient route 
which was at one time quite direct, but the phylogenetic en- 
largement of the forebrain has carried the recessus neuroporicus 
and the seat of the neurones ever farther and farther apart. 
The neurones of the nucleus neuroporicus probably func- 
tion as an olfacto-motor centre, supplementary to the chief one 
represented by the general striatum. The relations of this 
nucleus to the pallium will be discussed under the following 
subsection. 
4. The Pallium. 
The neurones of the pallium lie chiefly in what are called 
in this paper the pallial eminences ; see Fig. 1 and Fig. 31, p. e. 
I have introduced the definitive term pallial eminence for the 
hemispherical roof of the dorsal diverticulum of each lateral . 
ventricle (Fig. 31, p. v.). The earlier anatomists had observed 
the presence of these elevations in certain selachian forebrains, 
but their place in the organization of the pallium has not been. 
_ recognized heretofore. A pallial eminence is the seat of a 
crowded group of neurones, and the elevated condition of the 
mass has probably arisen from the disproportionately rapid 
growth which occurs here. 
The superficial zone of a pallial eminence is occupied almost 
exclusively by axis-cylinders, the significance of which will be 
noticed presently. The neurones lie in a crowded aggregate 
just within. Fig. 38 shows a representative group of these neu- 
rones. They are seen to embrace several varieties of form and 
size, all disposed without arrangement into definite layers. 
a. Neurones of the Tractus Pallia.—The external features 
