The brain of Acipenser. 235 
membraneous pallium in Acipenser with the base of the fore brain 
may possibly be compared with it. The tract to the ganglion 
habenulae, tractus olfacto-habenularis, comes from the olfactory area 
along the base of the fore brain including the nucleus taeniae, and 
runs beneath and behind the commissura anterior. This tract is 
more extensive in Acipenser, the groups of cells at the anterior end 
of the fore brain contributing to it a large bundle of fibres which 
runs above the anterior commissure. In my preliminary paper (98a) 
I stated that this tract probably contained fibres from the region to 
which I gave the name “cortex”, and for these fibres I used the 
name tractus cortico-habenularis. EDINGER (Bericht, ’97—98) has 
made an objection to this and I am convinced on further thought 
that the name is inappropriate, since any cells in the base of the 
fore brain which receive olfactory fibres and give rise to fibres to 
the ganglia habenulae are necessarily cells of the area olfactoria. If 
any cells of this region deserve the name of cortex, they are only 
the ones which give rise to commissural fibres to the epistriatum of 
the other side. I therefore withdraw the name tractus cortico- 
habenularis as applied in the previous paper (cf. page 145). 
In addition to the above mentioned tracts, there are in Acipenser 
tracts from each part of the area olfactoria to the hypothalamus 
(cf. page 144). Although EpINGER states in a review of my prelimi- 
nary paper that “Die Faserung aus den Ganglien des Vorderhirns 
folgt dem allgemeinen Fischtypus” (Bericht, ’97—98), it does not 
appear that the bundles from the olfactory nuclei have been described 
in detail before. They are presumably contained in EDINGER’s tractus 
strio- thalamicus, but the origin of a part of the fibres of that tract 
in the olfactory nuciei had not been pointed out, nor had the course 
and place of ending of such fibres been described. 
co) Cortex. 
The problem of the origin of the cerebral cortex and its homo- 
logy in lower Vertebrates has been re-opened in recent years, chiefly 
by STUDNICKA. His papers have been answered by RABL-RÜCKHARD 
and others (for papers on both sides, see list at end). STUDNICKA 
has been recently supported by two authors, F. MAYER (97) and 
HALLER (98). The opposed views, as I understand them, may be 
stated thus: according to RABL-RÜCKHARD’s hypothesis, the basal 
ganglion of the fish fore brain corresponds to the corpus striatum 
of the higher Vertebrate brain, while the membraneous roof cor- 
