No. 2.] EPIPHYSIS OF TELEOSTS AND: ANIA. 257 
1. When we compare the account of the development of the 
epiphysial vesicles in Lacertilia, as given by Béraneck (87), 
Frangotte (88), Strahl and Martin (88) and Leydig (90), with 
the account as I have given it for Teleosts, we find many points 
of resemblance. 
a. In both Lacertilia and Teleosts the vesicles arise as two 
small outgrowths in the posterior part of the roof of the 
primary fore-brain. According to Béraneck, Hoffmann and 
Leydig, the epiphysial vesicles in Lacerta agilis, 3 mm. long, 
communicate with one another, and have a common median 
opening into the brain-cavity below. This statement is 
supported by a figure of a longitudinal section through the 
vesicles, in which the posterior wall of the anterior vesicle is 
represented as passing directly into the anterior wall of the 
posterior one, while the anterior wall of the former and the 
posterior wall of the latter are directly continuous with the 
brain-roof. (See Béraneck, Fig. 9, and Hoffmann, Figs. 1 and 
2.) This is the same relation that the epiphysial vesicles bear 
to one another in Teleosts, as is shown in Figs. 4 and 5 of this 
paper. These two figures represent nearly transverse sections 
of Salmo and Catostomus, and the epiphysial vesicles in these 
forms therefore lie nearly in a transverse plane. In Stizostedion, 
Lepomis and Coregonus the anterior vesicle lies cephalad of 
the posterior one, but to the left of the median plane, and has 
therefore a position intermediate between the position it has 
in Lacertilia and the position it has in Salmo and Catosto- 
mus. In the stages earlier than that shown in Figs. 4 
and 5, each epiphysial vesicle in Salmo probably communi- 
cates with the brain cavity by a separate opening, as shown 
in Fig. 3a. 
These facts seem to me to indicate that these vesicles arise 
separately, and that, as they grow in a dorsal direction, they 
carry a part of the brain-wall with them, and thus form the 
common median passage which is shown in Figs. 4 and 5. 
The only reason for regarding the antertor vesicles as formed at 
the expense of the distal end of the posterior vesicle.ts that tt ts 
smaller, and, aside from this single fact, one might with equal 
force consider the posterior vesicle as formed at the expense of 
