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brain according to RACOVITZA have originated, but to each 
of them corresponds a ganglion ora pair of ganglia applied 
to a sense-organ. These are the “ganglions palpaires”, which 
belong to the “cerveau antérieur”’, the “ganglions optiques” 
and “antennaires”, which belong to the “cerveau moyen’ and 
the “ganglion nucal”, belonging to the “cerveau postérieur”. 
Now the nuchal pits are certainly dorsal structures and 
so are accordingly the oltactory lobes of the Annelid brain. 
Of the eyes it is not so easy to say whether they belong 
to the dorsal or to the ventral side of the prostomium. In 
the adult Annelid they are usually situated on the dorsal 
side, in the trochophora and in somewhat further advanced 
pelagic stages we find them situated nearly laterally but 
somewhat more to the ventral side. Often the ventral 
situation is even very evident, in Annelid as well as in 
Mollusc trochophora-larvae. I therefore believe that the eyes 
must be regarded as originally ventral structures, and this is 
in accordance with the circumstance, that they are closed round 
when the ventral half of the apical plate folds in to become the 
fore-brain in Vertebrates, while this is not the case with the 
olfactory pits. Finally we may regard the “cerveau antérieur” 
as terminal and neither ventral nor dorsal in its origin. 
Thus only the optic nervous centre of Annelids is involved 
at the closing of the cerebral plate in Craniates and probably 
may be found again in the optic ganglia of the retina (the 
Superficial granular and fibrillar layers) and in the region 
of the chiasma. In front of the latter we find in lower 
Craniates, especially in fishes, the strongly developed basal 
ganglia as thickenings of the lamina terminalis — corres- 
ponding to the corpus striatum of higher Vertebrates — while 
the roof of the forebrain, the pallium, consists here merely 
of a thin epithelium, without nerve cells. In higher Verte- 
brates the pallium: more and more develops, producing the 
hemispheres which take over the function of the basal 
gang!ia as an olfactory centre, until in Mammals the corpus 
striatum sinks into obscurity by the enormous development 
of the pallium. Can we compare these basal ganglia with 
one of the three centres of the Annelid brain, especially 
with the olfactory centre? [ do not think so, at least not 
directly, for the “Riechlappen” or “cerveau postérieur” 
Originate, as shown by KLEINENBERG, in close connection 
with the olfactory pits. Such is not the case with the basal 
ganglia of Vertebrates; they take their origin from the part 
