30 
GEORGE E. NICHOLES. 
and representing a sagittal section tlirougli the brain of a 
teleost, Cynoscion regale (’00, p. 39, tig. 1), the other 
(b) from his latest paper, representing a similar section 
tbrongh the brain of another teleost, Potnatomns salta- 
trix (’04, p. 209, fig. 1). The brains of both of these fishes 
had been studied by him when the preliminary paper was 
written, where it was said of Reissner’s fibre (’00, p. 41) that 
— “ its course is the same in all except in so far as it is 
dependent on the size and relations of the ventricles and 
other parts of the brain, which differ in different species.” 
According to my own observations there never is a. 
posterior branch connected with either the torus or the 
“ Dachkern ” such as Sargent describes, and one is foi’ced to 
the conclusion that the introduction of this branch in the later 
paper (where its course and relations are described in terms 
practically the same as those applied erroneously to the entire 
fibre in the first instance) has been due to his neglect to put 
l ight the original mistake in identifying the posterior commis- 
sure as the torus. 
This impression nlay be a mistaken one, but it is of the 
utmost importance to emphasise the non-existence of the 
jiosterior branch, as it is upon its alleged presence that 
Sargent’s statements as to the connection of Reissner’s fibre 
with the cells of the torus and the “Dachkern” and the conse- 
quent homologising of these two structures principally depend. 
The anterior branch, which, so far as my own observations go, 
alone exists, and which, as explained above, was alone figured 
and described by Sargent, in his preliminary paper, is, there- 
fore, in his later work, necessarily described as having (in 
forms other than Teleosts) quite different relations. 
In Teleosts it is traced into the torus longitudinalis by 
a somewhat devious path through the “ Schaltstiick ” (pars 
i n tercalatus) and the posterior commissure, the adoption 
of such a route being explained by Sargent as due to the 
early development of the cells of the optic reflex apparatus, 
which “ send their axons into the ventricle from the median 
plane of the roof (PI. 7, fig. 47 3 PI. 8 , figs. 55, 56, 58,/a*\ 
