The brain of Acipenser. 153 
fibres run an independent course, each taking the shortest path from 
its cell in whatever part of the olfactory lobe, to its end-nucleus in 
the fore brain. In consequence, the olfactory tract is very diffuse 
and ill-defined. All parts of the slightly constricted neck connecting 
the olfactory lobe and fore brain are traversed by a larger or smaller 
number of these fibres. Only a small number of fibres from the 
olfactory lobe are gathered into a definite bundle. This bundle lies 
Bigeye 
near the mid-ventral line at the junction of the lobe with the fore 
brain and traverses the nucleus postolfactorius ventralis, then courses 
around the lateral surface of the nucleus postolfactorius lateralis and 
enters the epistriatum at its dorso-lateral border. I have traced the 
olfactory fibres with certainty to the epistriatum and the two nuclei 
postolfactorii. Although I have been unable to trace these fibres 
with certainty into the caudal part of the fore brain. owing to the 
