1903 - 4 .] Origin of the Epiphysis Cerebri in the Chick. 161 
Fig. 1 is drawn from a chick-embryo at the 50th hour of incuba- 
tion, and represents a transverse section of the thalamencephalon 
in the pineal region. The larger of the two evaginations lies 
distinctly to the left of the mesial plane (which is represented by 
the dotted line in the figure), while on the right side a much 
smaller evagination exists. The latter was found to he evident in 
the whole series of sections of the pineal region in this embryo, 
but it was in every instance much smaller than the left 
evagination. 
Fig. 2 is from a chick-embryo at the 60th hour of incubation, 
and represents a transverse section of the roof of the thalam- 
encephalon in the pineal region as in the previous instance. The 
resemblance between this fig. and the fig. No. 5 which illustrates 
Dendy’s paper (11) is most striking, as will he at once recognised on 
comparing the two. Fig. 2 shows with marked clearness the simul- 
PROC. ROY. SOC. EDIN. — VOL. XXV. 11 
