264 C. JUDSON HERRICK 
The anuran amygdala in emerging from the urodele strio- 
amygdaloid complex of the ventrolateral nucleus has assumed all 
of the olfactory, habenular, and hypothalamic connections of 
the ventrolateral area—connections which, however, it shares 
with the overlying pyriform lobe. It possesses, moreover, some 
features which are not shared with the pyriform lobe, viz.: 
1. The commissural connection with the opposite amygdala 
in the anterior commissure. The commissural fibers of the 
pyriform lobes in mammals pass through the hippocampal 
commissure, a strictly pallial formation (dorsal psalterium, 
Cajal, 11, p. 715). In the frog also some fibers of the hippocam- 
pal commissure pass through the primordial hippocampus, 
around the dorsal angle of the hemisphere, to arborize throughout 
the entire pyriform lobe (P. Ramén y Cajal, ’05, pl. 16, fig. 4). 
I have seen similar fibers from the hippocampal commissure 
curving around the posterior pole of the hemisphere to reach 
the pyriform lobe. 
2. In the frog the descending fibers of the olfactory projection 
tract seem to come chiefly (perhaps exclusively) from neurons 
of the amygdala, while the ascending fibers of this tract terminate 
freely in both the amygdala and the pyriformlobe. In mammals, 
on the other hand, Cajal (’11, p. 721) describes the fibers of this 
tract as arising chiefly as axons of cortical neurons of the pyri- 
form lobe, though he believes that some fibers arise also in the 
amygdala. The absence of a true cortex in the amphibian 
pyriform lobe probably accounts for this difference. 
3. The secondary olfactory connection of the amygdala is 
specifically derived from the vomeronasal formation. This point 
suggests some further reflections. . 
The absence of the vomeronasal organ in fishes, its very rudi- 
mentary condition in urodeles, especially the lower forms, and 
its close association in many types with the posterior nasal 
aperture suggest that its primary function is in some way linked 
with the reception of sensory substances coming from the mouth 
cavity, though from the-relations in higher forms it may be 
inferred that this primary function ‘has been subject to further 
modification. 
