OF DENISON UNIVERSITY. 
41 
are occupied chiefly with fibres, especially ectad. There are also 
scattered cells lying laterad and ventrad of the nidulus of the habena, 
which stain very feebly. These are multipolar or bipolar, with occa- 
sional flask-cells like those of the rest of the thalamus. Meynerf s 
bundle enters this nidulus from behind. This seems to be what has 
been described in Vol. V of this bulletin, page 76, as the nidulus of 
Meynert’s bundle, though differing considerably in form and position 
from the arrangement there presented. This nidulus of Meynert’s 
bundle has also been described in reptiles, though there much further 
caudad and ventrad.* 
The fibres of Meynert’s bundle pass caudad beneath the taenia re- 
ceiving some fibres from the latter, as far as tl^i' superior com- 
missure. At this point they turn abruptly, pass caudo- . entrad through 
the thaltmus, cross the fibres of the third nerve near their exit, and 
disappear. The taenia thalami pass cephalo^ ventrad from the crus of 
the epiphysis, lying dorsad of the median, denser cell-cluster, or nidu- 
lus of the habena. They take the usual course, passing ventrad and 
laterad and at least at first somewhat caudad behind the anterior com- 
misure, soon to be lost among the peduncular fibres. 
The CojnmissiLral Apparatus of the Habence and Optic Lobes. In 
this region there are two commissural systems, the first cephalad, the 
second caudad of the epiphysis. The first system comprises the superior 
commissure and the commissure of the habenae. These commissures 
are distinct in the lizard, f but in these types are fused. The whole 
may here be called the superior commissure. It is horseshoe shaped, 
the convexity being caudad and dorsad. Plate II, Figs. 9 to 12, illus- 
trates these commissural systems in Geomys. Fig. 10 shows fibres from 
the lateral parts of the habenae arching caudo- dorsad toward the me- 
son, which, however, they do not quite reach at this level. Fig. ii 
"■'C. L. Herrick, “Topography and Histology of the Brain of Certain Rep- 
tiles,” Journal of Comparative Neurology, Vol. I, p. 26. 
“If the superior projecting portion of the habena surrounding the base of 
the stalk of the epiphysis be considered the habena proper, the deeper and more 
ventro-caudad portion may be distinguished as the nidulus of Mynert’s bundle, 
or nidulus Meynerti. The fibres of Meynert can be traced to the portion men- 
tioned (which in the black snake forms a distinct nidulus.) The cells are rather 
larger than those of the habena, and less compactly clustered about the walls of 
the third ventricle extending some di§tmice ventrad.” 
tC, I>. Herrick, loc. cit. 
