THE AMYGDALA IN AMPHIBIA 239 
of the nasal sac. In urodeles the supposed representative of. 
this organ is a lateral pouch from the much simpler nasal sac. 
In both cases the recess in question is lined with sensory olfactory 
epithelium. For figures of the nasal organ of Amblystoma see 
Bawden (94) and Zuckerkand1 (10). 
It has long been recognized that in some urodeles there is an 
accessory olfactory bulb, less clearly separated from the remainder 
of the bulb than in the frog, which receives a separate posterior 
and lateral division of the olfactory nerve. In Amblystoma 
Coghill (’02, pp. 209 and 253) demonstrated the course of the 
posterior division forward, first lying laterally of the anterior 
division, then ventrally of it, and finally turning abruptly lateral- 
ward to connect with the sensory epithelium of the lateral pouch 
termed Jacobson’s organ. He does not exclude the possibility 
of a certain: amount of interchange of fibers between the poste- 
rior and anterior divisions, and our Golgi preparations in fact 
do demonstrate some mingling of these fibers. 
I have verified Coghill’s description on old larvae of Ambly- 
stoma punctatum taken a few days before the metamorphosis, 
save that I have not been able on this material to trace the fibers of 
the posterolateral division of the olfactory nerve separately from 
the others of the common trunk for a short distance. These 
fibers course, as described by Coghill, along the ventral border 
of the common trunk. Farther rostrally, immediately caudad 
of the level of the choana, this common trunk breaks up into 
numerous branches, several of which from the ventral border 
of the trunk turn laterally along the ventral surface of the nasal 
sac. One of these supplies the olfactory epithelium of the lateral 
diverticulum (the supposed vomeronasal organ), others supply 
the ventral olfactory epithelium medially and caudally of this 
organ. The peripheral twig which supplies the lateral diver- 
ticulum is much smaller than the posterolateral division of the 
intracranial course of the nerve which terminates in the accessory 
bulb, and the indications are that this division contains fibers 
from some of the other peripheral lateral branches referred to 
above. 
