( 706 ) 
ventralis (fig. I and H, 8. rh. d. and S. rh. v.). The ventral edge 
of this thickened part of the mesial wall forms a prominence, which 
goes over in a crest, the erista ventralis rhinencephali. 
This crest first runs in fronto-occipital direction and then turns 
more ventrally over tne posterior wall of the funnellike outgrowth 
of the rhinencephalon where it goes over continuously in the same 
formation proceeding from the stratium. This is clearly seen in figure II 
(Cr. v.) where the ventral erista is seen on the posterior wall of 
the depression of the rhinencephalon cut in a very oblique direction. 
The line described by this ventral border of the corpus striatum 
and thickened part of the rhinencephalon has, looked at as a whole, 
the form of a horseshoe with its top directed to the occipital pole 
of the brain and meantime turned ventrally, while its opening is 
turned to the frontal pole of the hemisphere vesicle. The connection 
of rhinencephalon and striatum, which lies initially in the base of the 
brain comes with the outgrowth of the rhinencephalon partly on the 
posterior wall which borders the cavity, that proceeds in the olfact- 
ory lobe. This connection between striatum and rhineneephalon is 
therefore a primary one. 
The olfactory bulb in this stage of development of the rhinence- 
phalon is limited by a circular groove, the suleus circularis bulbi 
(Fig. I, H, Se. b), which deeply cuts in on the frontal pole of the 
bulb, becomes more flat on both sides and is seen as a round 
shallow groove at the posterior pole of the bulb (Fig. V S. ce. b.). 
The top of the bulb is turned to the mesial side and in a slightly 
forward direction, while the form of the bulb can be seen in the 
diagrammatic drawing figure V. 
The nerves which belong to the formation of the rhinencephalon 
are of two different kinds, and leave the brain at two different 
places. The first kind of nerves proceed from the top of the olfactory 
bulb. They are easily recognised by the fact, that their nuclei are 
small and not very numerous, so that the fundamental substance in 
which they are imbedded is distinctly seen. 
These nerves split up into very small tracts in the neighbourhood 
of the mucous membrane of the nose, where they seem to end. These 
nerves, which contain the olfactory nervefibres do not have any 
connection with the ganglion olfactorium. They all pass along this 
ganglion. 
The second place from where the nervefibres proceed is given by 
the mesial part of the suleus circularis bulbi. These nervefibres can 
be differentiated from the olfactoryfibres by the fact, that their nuclei 
are a little larger, and more numerous than the nuclei of the 
