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dilafed. The ciliated pits here arise at the dorsal edge of 
the little apical plate, a considerable distance in front of 
the prototroch. 
Homology of olfactory pits of Protostomians and Craniates. — 
This situation of the ciliated pits in Annelids on the dorsal 
side of the prostomium corresponds to the ventral side of 
the prostomium of Chordates, where we find just such a 
pair of ciliated pits, the olfactory grooves. It seems hardly 
possible to deny the weight of this complete agreement 
not only in their function and mode of origin, as 
observed by KEPNER and CASH (1915), but also, as appears 
now, in their situation. Especially in connection with 
our results for the optic and auditory organs, the conclu- 
sion seems inevitable that the olfactory organs of Craniates 
must also be derived from the corresponding organs in 
Annelids. 
Three main sense-organs inherited from Annelids. — Thus 
the rudiments of the three principal sense-organs of the 
Craniate head are older than the Vertebrate stock itself 
and have been inherited from the Annelids. During the 
preparation of the present second publication on my 
theory, five years after 1 had first worked it out, IT was 
pleased to find that the same idea, as well as so many others 
at which l arrived, has been anticipated, indeed has been 
already put forward, though very shortly and cursorily, by 
HATSCHEK in the year 1878 (p. 116). He has never 
reverted to it and soon afterwards seems to have abandoned 
the idea of an Annelidan origin of Vertebrates *) and to 
have adopted a quite different conception of the origin 
of the Craniate fore-brain (cf. p. 222). His suggestions, 
however, so closely approach my own results that 1 will 
quote them here in extenso, and add the figure which 
served to illustrate them (fig. 14). 
“Die Scheitelplatte’”, says HATSCHEK, “und die Anlage der 
Schlundcommissur der Anneliden ist, unserer Ansicht nach, 
dem vordersten Theile der Medullarplatte, aus welchem 
sich das Gehirn der Wirbelthiere entwickelt, homolog. 
1) In 1911 at least HATSCHEK declares that the first view of an 
Amphioxus-embryo, fished in the Pantano, as aliving argument “alle 
meine früheren Vorstellungen der Annelidenverwandtschaft der 
Wirbeltiere im ersten Moment hinwegfegte”, 
