216 C. JUDSON HERRICK 
the ventrolateral olfactory tract from the vomeronasal formation 
and will be here termed the amygdala. Our attention in this 
paper will be chiefly directed to the structure and connections 
of the amphibian amygdala. 
The terminology of the amphibian forebrain is in great con- 
fusion. The usage here employed conforms in general, except 
as noted, with that of my contribution published in 1910. 
The cerebral hemisphere of the frog is divisible into five regions, 
the olfactory bulb and four quadrants termed dorsomedial, ventro- 
medial, ventrolateral, and dorsolateral. The dorsomedial quad- 
rant is the primordial hippocampus; the ventromedial quadrant 
is the septum, using this term in its broadest sense; the ventro- 
lateral quadrant includes the very undifferentiated corpus 
striatum and the amygdala, which is a sharply defined nucleus; 
the dorsolateral quadrant comprises the lateral olfactory nucleus 
and the pyriform lobe, which are relatively undifferentiated and 
not clearly separable from each other. 
All four quadrants converge into an undifferentiated anterior 
olfactory nucleus at the base of the olfactory bulb, and the two 
dorsal quadrants converge into an undifferentiated area at the 
posterior pole of the hemisphere. Comparison with higher 
brains shows that the dorsal quadrants are primordial pallium 
(the dorsolateral incompletely so), but the ventral quadrants are 
essentially basal nuclei and do not in any vertebrate give rise to 
true cerebral cortex. The general relations of the amphibian 
cerebral hemispheres to those of other ichthyopsid forms are 
reviewed in a recent paper (Herrick, ’21). 
This account is based upon a collection of several hundred 
brains of urodele and anuran Amphibia prepared by various 
methods by Dr. Paul 8. McKibben, upon about 150 brains of 
larval Amblystoma prepared by the Golgi method by Dr. Charles 
Brookover, and upon about 150 brains of adult and larval 
Amblystoma variously prepared in this laboratory by my assist- 
ant, Miss Jeannette B. Obenchain. To these careful workers 
I acknowledge my deep indebtedness. 
