16 Paraphysis and the Pineal Regign in Necturus Maculatus 
its cavity seems to be divided more or less into compartments. Fig. 21 
represents a wax reconstruction of an adult epiphysis seen from -above. 
It is irregularly triangular in shape with a broad base and a blunt apex. 
Its surface is grooved more or less by vessels which lie against its walls. 
Fig. 22 is the same model with the top removed. ‘The interior is more 
or less subdivided by incomplete septa. At its apex there is a small cavity 
‘Fic. 22. Same as Fig. 21, with top of epiphysis removed. 
bounded behind by a partial septum, then comes a large chamber, which 
divides into two passages running back towards the angles at the base. 
Between these two passages appears a comparatively solid area, inter- 
rupted, however, to some extent by small spaces, which communicate with 
each other and the larger chambers. This solid area lies over the stalk 
of the organ. The supra commissure appears to be comparatively small, 
D.PIx. E 
Fig. 23. Brain of adult necturus. Viewed from above. X 7 diams. 
while the posterior is large and forms a deep groove in the roof of the 
brain. Fig. 23 is a view of the brain of an adult necturus showing the 
relative positions of paraphvsis and epiphysis. The tufted extremity 
of the diencephalic plexus can be seen in the fourth ventricle. 
If Fig. 1, the embryo of 8-9 mm., is compared with Fig. 17, the adult, 
one sees that the paraphysal arch has been wholly taken up in the 
formation of the telencephalic plexus, the plexus of the hemispheres, and 
