OF DENISON UNIVERSITY. 79 
The greater part of this cortex pertains to the crus and may be there 
considered. 
Crus olfactorius. The crus terminates in the pes obliquely, the 
lateral and dorsal portions being longest. Ventrally it is chiefly made 
up of the radices of tracts .from the pero. There are three such fibre- 
bundles ; the largest, or radix pedis lateralis, is an exceedingly strong 
band, as in rodents. Its development stands in direct proportion to 
that of the olfactory lobe and this, in turn, with that of the hippo- 
campus. The fibres collect in the granular layer of the pero and then 
about the ventricle, accumulating chiefly mesad and ventrad. On 
entering the pes they encounter the invading cortex cruris and are 
driven ectad, thence laterad superficially to the cortex cruris, where 
they form a strong bundle passing caudad and somewhat laterad along 
the fissura radicis to the lobus pyriformis, thence for the most part to 
cross mesad and entad into the hippocampus, especially the fornicate 
gyrus. The tract of the fibres caudad is not compact but they spread 
out to some extent upon the pyriform. The fibres of this ectal olfac- 
tory tract are in part overlapped by fibres of a different character. 
The radix pedis mesalis, on the other hand, is very small and dis- 
perse. Its fibres, which arise on the ventral and mesal, as well as 
especially in the meso-dorsal part of the crus, pass in the neuroglia 
layer and remain ectad to the cell zone until reaching the neighbor- 
hood of the splenialis fissure, where they cross to the gyrus fornicatus. 
The bundles do not unite to form a single tract but remain largely iso- 
lated from each other. 
There is no external indication of a radix pedis intermedius, but 
we encounter a few bundles which apparently arise from the ventral 
part of the crus and passing caudad through the substance of the lobus 
post-rhinalis emerge mesad and ectad to unite with the bundles of the 
radix mesalis on their way to the gyrus fornicatus. The fibres enter 
the peduncular tracts in their dorsad course and pass through them. 
As indicated above, the dorsal, lateral and mesal aspects of the crus 
are covered by cortical masses. 
Thus far we have been dealing with tracts which undoubtedly 
pertain to the olfactory pero or ganglion proper. Greater difficulty 
arises in construing the so called ental olfactory tract (radix mesalis of 
fishes.) Following suggestions arising from these studies, Mr. C. 
Judson Herrick has investigated the relations of the cortex cruris to 
the pero, in rodents. He arrives at the conclusion (BuL Denison 
