270 C. JUDSON HERRICK 
and such a connection has often been described by others (e.g., 
Edinger, ’11, p. 389.) 
In any case, it is clear from Cajal’s description that the entire 
amygdaloid complex of the mouse is under indirect, if not direct, 
influence from the lateral olfactory tract, for it is enveloped by 
cortex of the pyriform lobe and is penetrated by axons from 
these cortical neurons, which in turn receive fibers from the lateral 
olfactory tract directly. There is also a “tangential tract of the 
amygdala” (Cajal, ’11, p. 725, fig. 463, d) between the distribution 
area of the lateral olfactory tract and the presubicular area of 
the amygdala. 
Rothig (’09), in Didelphys marsupialis, describes a nucleus 
amygdalae under the pyriform lobe and rostrally of this two 
cellular areas which are probably to be regarded as parts of the 
amygdaloid complex as this is usually defined in mammals. One 
of these is a large-celled nucleus occupying the angle ventrally 
of the pyriform lobe which receives fibers from the lateral olfac- 
tory tract; this he terms nucleus of the tractus bulbo-corticalis 
(our lateral olfactory tract). The second nucleus (his nucleus 
taeniae semicircularis) lies dorsally and internally of the first 
and in very close association with it. From it arise fibers of the 
stria terminalis (his pars ventralis taeniae‘). 
Kappers (’08, p. 241) describes in Hypsiprymnus an origin of 
stria terminalis fibers from a similar nucleus of the lateral olfac- 
tory tract and nucleus taeniae. These two nuclei in the aggre- 
gate probably correspond pretty closely with the medial large- 
celled nucleus of Johnston (’15, p. 415) in the turtle and the 
ventromedial nucleus of Crosby (717, p. 348) in the alligator. 
In rodents the relations are much the same. My observations 
on the brain of the rat show (in conformity with previous de- 
scriptions of rodents) that the most ventral component of the 
amygdaloid complex is the area presubicularis. This is a sharply 
circumscribed spherical nucleus of large cells lying close to the 
surface at the rostral end of the pyriform lobe in much the same 
4My own observations upon the opossum, Didelphys virginiana, suggest 
that Réthig’s account of the relations of the pars ventralis taeniae requires 
revision, but the discussion of this matter must be reserved until a later time. 
