240 Cc. JUDSON HERRICK 
Coghill is correct, I have no doubt, in tracing the fibers from 
the lateral diverticulum of the nasal sac into the accessory bulb, 
for in well-preserved material this fascicle can probably be 
readily followed separately; but my material suggests that the 
incompletely differentiated accessory olfactory bulb receives also 
many fibers from other parts of the nasal sac. 
From these observations and from the accounts in the litera- 
ture it may be concluded that the nasal sac is much more simply 
organized in Urodela than in Anura, and that if a*true vomerona- 
sal organ is present in the former it is a small lateral diverticulum 
of the simple sac. In Amblystoma the olfactory fibers from this 
diverticulum terminate centrally in an incompletely differentiated 
accessory olfactory bulb which also receives other fibers probably 
derived from the ventral wall of the nasal sac. 
These relations strongly suggest the partial homology of the 
posterolateral division of the olfactory nerve with the anuran 
vomeronasal nerve and the accessory bulb with the vomeronasal 
formation; but these names will not be applied to the urodeles 
in the following description for reasons which will appear in the 
discussion on pages 255 and 264. 
The olfactory bulb and lateral olfactory tract 
In adult Amblystoma the olfactory bulb is strictly lateral in 
position (Herrick, ’10, figs. 8 to 11; Bindewald, ’14, figs. C to F) 
and occupies the whole thickness of all or part of the lateral wall 
of the cerebral hemisphere for about half the distance from the 
rostral end to the level of the interventricular foramen. The 
caudal end of the bulb (bulbulus accessorius of Bindewald, 714, | 
fig. B) is not so clearly separated from the remainder as in the 
Anura. 
The olfactory bulb as a whole forms a considerable eminence 
on the external surface of the brain and also a projection into 
the rostral end of the lateral ventricle. The ventricular eminence 
is in some preparations separated by a slight internal sulcus into 
larger rostral and smaller caudal portions, thus marking on the 
ventricular surface the rostral boundary of the accessory. bulb. 
This sulcus is visible only in well-preserved material free from 
