Houser, Zhe Neurones of a Selachian. I51 
ferent place in the olfactory apparatus from the epistriatum. 
The latter appears to be a sensory gateway to the striatum, 
while the postolfactory neurones enter into direct relations with 
the posterior regions of the brain. 
3. The Nucleus Neuroporicus. 
A group of neurones situated in the region of the recessus 
neuroporicus gives origin toa special bundle of the tractus 
strio-thalamicus, the Jedianbiindel of EDINGER (’88). I shall 
designate this group the xucleus neuroportcus. The neurones 
of the nucleus neuroporicus lie chiefly behind the external 
opening of the neuropore, just beneath the surface of what is 
really the most anterior part of the pallium. Other neurones 
of the same group are found at deeper levels, in the striatum, 
of course. The entire group is distributed, therefore, without 
regard to the anatomical boundaries which we seek to draw be- 
tween the pallium and the striatum. 
A sagittal section of the neuroporic nucleus stained by 
the Gorter method exhibits a bewildering nervous tangle. The 
components of this plexus are the processes of the intrinsic 
neurones, and the terminations of the olfactory fibres which 
sweep over from the tractus. The nucleus is seen, then, to be 
an additional olfactory centre. 
Two neuroporic neurones are shown in Fig. 37, exclusive 
of the maze of nervous processes in which they lie. The cell- 
body is large, the largest, in fact, of any found in the fore-brain. 
Its form is quite distinctly polygonal, the number of sides being 
determined by the number of dendrites. The dendrites are very 
thick at their bases, and they are some three to five in number. 
Each one soon breaks up into large branches. The length of 
a dendrite is relatively short. Its surface exhibits thickenings 
and minute knobs sparingly distributed. 
The axone may arise from the cell-body, but in most in- 
stances its origin is traceable to the thick base of one of the 
dendrites. The several axones from each lateral half of the 
nucleus run anteriorly to the level of the neuropore, where 
they curve upon themselves to follow the course of that chan- 
