534 
noticed further that the rostral end of this sulcus externus always 
passes above the olfactory bulb. 
In adult teleost forebrains, especially in those most highly devel- 
oped and most strongly everted, certain other ventricular sulci appear 
and become deeper and more striking than those that I have mentioned. 
These Dr. KArPpErs has described in Bd. 40, No. 1, of this Journal. 
I wish only to remark that these sulci are the result of the last stages 
in the differentiation of the teleost forebrain, and that they are phylo- 
genetically and ontogenetically the latest landmarks in the fish brain. 
Their significance, therefore, is to be determined by a study of the 
internal structure and connections of the grey masses related to them. 
I have suggested elsewhere that part of these furrows may owe their 
origin to the mechanical influence of the anterior commissure. The 
commissure is well developed long before these sulci appear in the 
ontogeny, and the topography of these sulci at the time of their develop- 
ment in Amia, Ameiurus, and other forms strongly suggests that they 
are due in part at least to the binding down of the brain substance 
by the bundles of the anterior commissure. If these sulci are due 
to any such mechanical causes it is evident that they can not give 
primary evidence as to the functional significance of the gray masses 
bounded by them. 
My studies show that the ventricular gray of the “striatum”, 
“epistriatum” and “tuberculum taeniae” of KAPPpErs’ fig. 7 presents the 
same histological characteristics and essentially similar connections 
throughout. These facts are vastly more important than the recently 
developed ventricular furrows which KAPPERS describes. 
The greater part of Dr. KAPPpERrs’ paper is devoted to criticisms 
of the work of the present writer. First, KAPPERS attempts to show 
that the writer has only recently accepted the explanation of the ever- 
sion of the teleost brain given by Mrs. GAGE in 1893. With regard 
to this I have only to call attention to fig. 151 in my book “The 
Nervous System of Vertebrates”, which is reproduced here (Fig. 5). 
In this figure I illustrated the translocation of homologous structures 
in cyclostomes, selachians, ganoids, teleosts and amphibians. In the 
accompanying text I commented upon the eversion of the teleost brain, 
although I used somewhat different terms from those used later by 
Kappers. Part of this work was written at the Zoological Station in 
Naples in 1904 and this figure was drawn at that time. The writer 
understood the eversion of the teleost forebrain in 1904 when, as 
Kapprrs tells us, he first directed his attention to this subject. 
KAPPERS and THEUNISSEN (1907) first published their comments on 
