56 PINEAL EYE 
character, its visceral and outer openings bearing grooves 
and ridges which demonstrate that the pineal structures 
must not only have been paired, but must have entered 
the opening in a way which precludes the admission of 
the epiphysis. It is now, therefore, that the pineal fora- 
men which has been described in Siluroids * becomes 
of especial interest, since its contained structures are ap- 
parently connected with the lateral line system of paired 
nerves. 
It must for the present be concluded, accordingly, that 
the pineal structures of the true fishes do not tend to con- 
firm the theory that the epiphysis of the ancestral verte- 
brates was connected with a median unpaired eye ; it would 
appear, on the other hand, that both in their recent and 
fossil forms, the epiphysis was connected in its median 
opening with the innervation of the sensory canals of 
the head. This view, it is now interesting to note, seems 
essentially confirmed by ontogeny. The fact that three 
successive pairs of epiphysial’outgrowths have been noted — 
in the roof of the thalamencephalon, appears distinctly 
adverse to the theory of a median eye. 
*Dean, V. Y. Rep. of Fisheries, 1891, and Klinckowstrém, Anat. Anz., 
1893, viii, p. 561. 
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** Ome ons eo ee ** 
