Cerebral Tract of Professor Owen. 285 
the funnel and nuchal valves), which are in some species also 
connected with locomotion, from their effect when inaction, also 
the organ of hearing ; and most posterior another portion, 
from which are derived visceral, branchial, and those large 
compound nerves given to the mantle. We may very fairly 
point out olfactory, optic, and auditory nerves, in their proper 
situation, oculo-motor, the fifth or tentacular (the pes anse- 
rinus of Cuvier), the seventh or siphonic, the vagus or great 
visceral nerve, and the pair of nerves which go backwards to 
the mantle and its muscles, and have been considered analo- 
gous to the spinal cord. The view advocated only trenches 
upon that of our Che in this, that the supposed guondam 
entry and exit of the cesophagus through the brain are re- 
versed. Both views seem strange enough; one must be true ; 
and we think this is less strange than the other. The new 
mouth appears to enter, in the vertebrate, on what corresponds 
to the siphonic or lower side—that is, apparently, where the 
yolk (in the sepia) is absorbed in the crop (protostome, see 
fig. 3) ; the mouth of the matured sepia has relation to the 
pituitary rather than to the pineal, and the exit of the cesopha- 
gus, vice versd, to the pineal rather than to the pituitary. 
Perhaps the inferior hypoaria ganglia of fishes may be ex- 
plained as remnants of the molluscan arrangement; but let 
that go. 
We are inclined, then, to believe that morphological fitness 
or conditions of existence must be considered as well as typical 
formation, the former often overriding the latter ; and whilst 
we concur in the terms neural and hemal in anatomy, the 
common terms dorsal and ventral, or others more anatomi- 
eally correct (say upper and lower), we think must be re- 
tained, though the two sets of terms are distinct. 
Admitting the truth and originality of Prof. Owen’s main 
proposition, it perhaps may still be held that less is required 
to believe, with Cuvier, that the subcesophageal nervous gan- 
glia in the Mollusca, which appear homologous with the me- 
dulla oblongata of the vertebrate, and so of the ventral cords 
of Articulata, which may be the homologue of the medulla 
spinalis, really occupy the ventral aspect of the body, than 
to adopt a view which ignores many other conditions and 
morphological considerations, and leads to such strong con- 
clusions. 
