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to that of Amphioxus than in the former, though there can 
be no question of a direct homologization of the two. This 
starting point of KUPFEER has been shown to be a false 
one, though his conclusion, that the end of the brain-axis 
of Craniates is found in the neuropore, is not therefore 
necessarily to be rejected and at any rate seems to me to 
be preferable to KIS's and HATSCHEK's assumption of 
a linear fore-end of the brain. No doubt both the latter 
investigators were right in emphasizing that the part of 
the brain in front of the infundibulum isa later acquisition, 
not yet present in the brain of Amphioxus, but their concep- 
tion of the way in which it has originated needs modification. 
The question of the axis of the brain has lost much of 
its importance in the light of my theory, which no longer 
permits a comparison of the fore-brain of the Craniates with 
the brain-vesicle of Amphioxus in the sense of V. KUPFFER, 
but, if we want to speak of a brain axis, l think it preferable 
to let it end in the neuropore which, just as in Amphioxus, 
designates the anterior termination of the dorsal suture. 
This implies, that the lamina terminalis represents the 
primary floor of the fore-brain, not a part of the original 
roof with a median suture, as supposed by HIS and others, 
Lateral sense-organs in Annelids. — \f our conclusions 
are hitherto correct, it must be admitted, that hardly two 
of the great sub-kingdoms or phyla of the animal kingdom 
show such a close agreement, even in the details of their 
structure, as Annelids and Vertebrates, and in no other 
case can the structure of the one be derived so complietely 
from that of the other. This consideration makes it appear 
not quite so improbable, that EISIG (1887) was not wrong, 
when he believed he had found again also the so-called 
sixth sense-ovrgan of lower Craniates in Annelids. After 
PARKER’s (1905) experiments the function of the organs of 
the lateral sense-line is the perception of water vibrations 
of low frequency, produced by the waves on the surface 
and by bodies falling into the water, while HOFER (1909) 
ascribes to them only the faculty of perceiving the constant 
pressure of water-currents. With the exception of Capitella, 
EISIG (1887, p. 501) finds in all Capitellids, nearly along 
the whole length of the body, in every segment a pair of 
roundish prominences, situated laterally between the neural 
and the haemal parapodium near the hinder limit of the 
segment. it is just on the boundary-line of haemal and 
