No. 2.] EPIPHYSIS OF TELEOSTS AND AMIA. 259 
Salmo the vesicles are separate outgrowths strengthens some- 
what Leydig’s ('90) view that they are separate and independent 
outgrowths in Lacertilia.! 
We should then interpret the position of the anterior vesicle 
of Stizostedion and Lepomis (in front and to the left of the 
posterior one) as representing a condition intermediate between 
that in Salmo (at the side of the posterior one) and that in 
Lacertilia (in front of the posterior one). In Anguis fragilis 
the position of the anterior vesicle, described by Strahl and 
Martin and Hoffmann as not in the median plane with the 
epiphysis, may also be interpreted as representing a stage 
intermediate between Salmo and Lacerta. If we regard the 
position in Salmo as the primitive one, some shifting must 
have taken place in the other forms. In this shifting the 
determining factor appears to have been the degree of develop- 
ment of the vesicles. Thus the relatively large size of the 
anterior vesicle of Lacertilia, due to its former functional 
importance, may have brought it into the median plane, because 
there was room for it only in that position. The epiphysis in 
Lacertilia may have come to lie in the median plane for the 
same reason. In Teleosts, on the other hand, the epiphysis 
alone becomes of considerable size, and the small anterior 
vesicle finds abundant room in its primitive position at the side 
of the stalk of the epiphysis. It is only in the early stages in 
Teleosts, when the two vesicles are large relatively to the brain 
and are nearly of a size, that crowding causes a partial displace- 
ment of both vesicles into the median plane. 
If we adopt the alternative hypothesis that the vesicles were 
originally anterior and posterior, it is difficult to understand 
1Since the above was written there has appeared a paper by Béraneck (Sur le 
nerf parietal et la morphologie du troisieme ceil des Vertébrés, Anatomischer 
Anzeiger, Band VII, Nos. 21 und 22), in which a nerve is described connecting 
the parietal eye with the brain in embryos of Anguis 24-27 mm. long. As this 
paper goes to press Klinckowstro6m (Le premier développement de l’ceil pineal, 
Vepiphyse et le nerf parietal chez Iguana tuberculata; Anatomischer Anzeiger, 
Band VIII, Nos. 8 und 9) records a similar observation on Iguana. Contrary to 
the conclusions of Klinckowstrém, these observations seem to me to go a long way 
toward establishing the independence of the epiphysis and parietal eye, since 
they indicate that the two structures are supplied by independent nerves which 
arise from widely separated brain-centers. 
