The brain af Acipenser. 159 
STANNIUS finds in sharks (Raja, Spinax, Carcharias) three 
roots in the V—VII complex. The first root is the same as in 
Pleuronectes. The third root (tab. 2, fig. 1, R. 2) is a very large 
dorsal root, “welche höher aufwärts entspringt . . . . Sie tritt aus 
dicht hinter dem Cerebellum und etwas auswärts von ihm, zur Seite 
des Sinus rhomboidalis hoch oben aus einer einwärts gelegenen Er- 
habenheit oder einem inneren Wulste des Corpus restiforme”. It 
is wholly coarse-fibred and sensory and evidently corresponds to the 
third root of Acipenser sturio. The second root of sharks lies close 
to VIII and consists of fibres of three kinds: coarse fibres from 
the “Corpus restiforme”, fine fibres which arise nearer to VIII, 
and coarse fibres which accompany the fine. This root contributes 
fibres to both the trigeminus and the facialis, the fine fibres being 
confined to the N. palatinus and the motor fibres forming the 
motor VII. STANNIUS states that this root is equal to the third 
and fourth roots of Teleosts which possess four roots (4th and 5th 
of Pleuronectes). But it is evident that the coarse sensory fibres from 
the “Corpus restiforme” can not belong to roots 3 and 4 of Teleosts, 
or roots 4 and 5 of Pleuronectes, which consist entirely of fine sen- 
sory and coarse motor fibres and go to form the N. palatinus and 
motor VII. These “Corpus restiforme” fibres in sharks are part 
of the lateral line components which we are considering and are 
equivalent to root 3 of Pleuronectes and to a part of root 2 of other 
Teleosts. StTannius’ root 3 of sharks is wanting as a distinct root 
in Teleosts. This is for the reason that the dorsal and inner ridge 
of the “Corpus restiforme” from which it arises in sharks is wanting 
in Teleosts. 
My object in this somewhat extended analysis of STANNIUS’ de- 
scription is to identify the central nuclei into which the lateral line 
roots enter, as well as to identify the roots themselves. It is un- 
necessary to follow the distribution of these components. It is 
evident that in Teleosts the central body into which the lateral line 
root or roots enter, the “Lobus posterior medullae oblongatae”, is 
that body which in all fishes is now known as the tuberculum 
acusticum. It is equally evident that in Acipenser sturio and the 
sharks described by SrTannius there is another more dorsally 
situated ridge which projects into the cavity and which he calls a 
part of the “Corpus restiforme”. He does not use the name “Lobus 
posterior” for this body. Into this most dorsal ridge there enters 
in A. sturio and the sharks a large nerve which he describes as 
