No. 3.] MUSCLES AND NERVES [IN AMIA CALVA. 725 
In young larvae the two anterior occipital nerves arise 
directly ventral to the two posterior roots of the vagus, often 
lying in the same transverse section with those roots. These 
two roots of the vagus arise, even in large larvae, considerably 
behind the other roots of the nerve, and run forward a rela- 
tively long distance internal to the occipitale laterale to join 
those roots. In one 12 mm. larva, cut in vertical sections, all 
the roots of the vagus were cut in one section. In that speci- 
men there were six distinct roots, all of fairly equal size, and 
all converging together to form the common root of the 
nerve. The posterior of these six roots was formed by the 
fusion of the two roots above described, and on these roots 
was found a considerable part of the intracranial ganglion of 
the nerve. If these two roots are, as they seem to be, the 
dorsal roots corresponding to the two independent ventral 
ones, we have, in Amia, four complete spinal-like occipital 
nerves, and a postoccipital, or first spinal nerve which must 
also be assigned, as its dorsal arch is, to the occipital region 
of the skull. The nerves thus indicate five vertebral segments 
fused with the hind end of the skull. If the last occipital arch 
be assigned to the first vertebra, there would be but four. 
In 12 mm. larvae the occipitale laterale is a piece of carti- 
lage running upward, outward, and forward, touching, or almost 
touching, at its upper end, the hind wall of the auditory cap- 
sule, but not fused with that wall. It is, however, connected 
with the wall by a line of tissue, in which cartilage later 
develops. At its lower end, which is much enlarged, it is 
imbedded, like the occipital and spinal dorsal arches, in the as 
yet unsegmented cartilaginous line of the dorsal processes. 
On the dorsal surface of its lower end there is a slight ele- 
vation, so that, in vertical sections passing through this por- 
tion, it has exactly the shape and appearance of the following 
occipital and spinal arches. It is, however, inclined forward, 
instead of backward as these arches are. The cartilaginous 
line of the dorsal processes here drops gradually from near the 
dorsal surface of the notochord to its lateral aspect, and in 
front of the occipitale laterale it is continuous with, or be- 
comes, the base of the skull. The notochord everywhere lies 
