220 
fused with the anterior ganglia of the ventral nerve chain, 
eye ru 
from which the Vertebrate brain is deri he di 
ments follo m and are incorporated. with the brain 
involution from which they grow out again to the surface À 
ganglia with the ventral nerve-chain needs to be assumed, 
however, if we apply the principles of my theory to this case. 
Bt en dad en De 
WAE ge ad elo es ee en Tiaii Ien ak bl k 
ostorfïitm soma 
mp: card. 
archeric. Ì 
Fig. 1. te of an Annelid, an Acraniate Chordate before the formation of 
ail has ele and a Craniate Chordate with tail (cf. erik HI). 
S de ‚ 4. p. animal pole, archenc. archencephalon, can. med. ul- 
as tube, zeur. Fi neuropore, p. card, cardiac pore, p. neur. meúrerderie 
pore, stom, Stomodaeum. 
Homology of Craniate and Protostomian eyes. — Thus we 
are led along a quite different path to a conclusion already 
indicated by a consideration of the relation of the fore- end 
of the notochord to that of the medullary tube, scil. that 
the praechordal part of the brain with the ‘optic vesicles 
which in Vertebrates have evidently developed along lines 
