206 J. B. JOHNSTON, 
b) Dorsal to this a fine-fibred decussation in the central grey 
of the aqueduct. 
4. In the region of the corpus interpedunculare, in ventro-dorsal 
succession : 
a) Decussation of MEYNERT’s bundle in the ganglion inter- 
pedunculare. 
b) Commissura ansulata, mostly a decussation of deep lateral 
tracts. 
c) Bindearmkreuzung. 
d) Commissure of fine fibres in the Bodengrau of the aqueduct. 
Comparing this with my analysis of the decussations in the same 
region, EDINGER’s 1 is too far forward in Acipenser, if present at 
all, to be considered a part of this complex; 2a is probably not 
present in Acipenser, while 2b corresponds to my 1. EDINGER’s 3a 
corresponds to my 2, 3 and 4, my analysis of the tectal bundles 
being carried farther than EpINGER’s. His 3b and 4b, c and d, 
I can not identify in Acipenser. His 4a is of course my 8, while 
my 5, 6 and 7 have not been seen by EDINGER. 
C. ’Tween Brain. 
a) Ganglia habenulae and their Tracts. 
MAYSER (’81) describes the taenia, the ganglion, and the bundles 
of MEYNERT. The latter bundles pierce the commissura ansulata in 
several parts which reunite. The medial fibres then decussate and 
end in the cephalic part of the corpus interpedunculare. The lateral 
fibres pass farther back and decussate caudal to the corpus. “An 
einer schräg nach hinten abfallenden Horizontalreihe von Cyprinus 
barbus sieht diese Kreuzung so aus, wie wenn man die Finger 
beider halb hohl gemachten Hinde zwischen einander steckt.” He 
does not know whether the fibres of the opposite sides join one 
another, or whether the fibres end in relation with cells which escape 
notice in this complex region, or in relation with cells, “welche in 
den nächsten Frontalebenen hinter dem Ganglion interpedunculare 
dicht gedrängt zu beiden Seiten der Raphe liegen”. The last he 
considers very improbable. It is possible that the nucleus here 
rejected by MAysER is the same as that in which the bundles of 
MEYNERT do end in Acipenser. 
AHLBORN (83) describes the ganglia habenulae and MEYNERT’S 
bundles in Petromyzon. The right bundle of MEYNERT is very 
