186 RALPH EDWARD SHELDON 
tractus olfactorius ascendens, while the medial bundle is most 
closely associated with the tractus olfactorius medialis. The 
olfactory bulb is closely applied to the caudo-mesal face of the cap- 
sule so that the nerve itself is very short, although individual 
fibers may be of some length. 
c. Ganglion of the nervus terminalis 
Lying between the two bundles of the olfactory nerve from the 
lamellae to the bulb are a number of large scattered ganglion cells 
forming the ganglion of the nervus terminalis. In the adult carp 
these cells are most numerous near the bulb and are apparently 
about a hundred in number. This is less than is the case in Amia 
as described by Brookover (’08, ’10). Neurites from these cells 
run mesad to form a bundle of fibers on the mesal aspect of each 
bulb (figs. 7, 123, 124). 
2. THE TELENCEPHALON 
a. Olfactory bulb and crus 
The olfactory bulb is ellipsoid in shape, about 1.5 mm. long and 
1 mm. thick, in a 40 em. carp. Rostrally and laterally it is cov- 
ered by a mass of olfactory nerve fibers as noted above. At the 
rostral end of the bulb a circular constriction appears externally, 
separating the bulb proper from the olfactory nerve proper, which 
rostro-lateral to the constriction spreads out over the olfactory 
capsule. Caudally the bulb tapers down to the small, elongated: 
crus on which it is borne in the cyprinoids. This is from three to 
four centimeters long in a 40 em. carp, extending from the bulbs to 
the cerebral hemisphere (fig.1). In young fry the bulbs are closely 
apposed to the hemispheres; but since the cranium grows faster 
than the brain as a whole, the crura elongate. Each crus is a 
hollow tube, the base of which is formed by the tracts connecting 
the bulb and hemisphere (figs. 2, 22, 23). Dorsally is an epithe- 
lial roof, a rhinotela, which is simply a rostral prolongation of 
the tela, or so-called pallium of the hemispheres, consisting ofa 
layer of ependyma and one of pia. This covering arches over the 
