OBSERVATIONS ON THE CRANIAL NERVES OF SCYLLIUM. 471 
connect directly the ganglion c.g. of the third nerve with the 
Gasserian ganglion at the root of the fifth. 
The second (figs. 10, 11, and 12, x) passes straight forward 
from the ganglion ¢c.g., running through the walls of the first head 
cavity under the rectus superior and rectus internus, and through 
the substance of the sclerotic on the inner surface of the eye- 
ball. Passing out from the orbit, immediately above the odliquus 
inferior, it still pursues its course straight forward, but becomes 
more superficial. In the earlier stages it crosses the root of the 
olfactory nerve, with which it lies in very close contact: in 
the later stages (figs. 12 and 15, nN) it is, rather more dorsally 
situated, and then crosses the ophthalmic branches of the fifth and 
seventh nerves at a considerable angle (fig. 12, ), and ends in 
the skin at the extreme fore part of the head. After careful and 
repeated examination we have failed to detect any branch given 
off from the nerve at any point of its length. 
At stage K all the above-mentioned branches of the third 
nerve are developed, except the upper branch, to the rectus 
superior and rectus internus, which we have failed to detect: 
the ganglion c.g. is very conspicuous, and the nerves NV.c. and WV. 
have the same structure and connections as at stage Nn, the 
latter of the two stretching forward to the extreme anterior 
part of the head, in the skin of which it ends. 
In the later stages the modifications which the third nerve 
undergoes are merely ones of detail, all the principal branches of 
the nerve being already established, and maintaining their relations 
practically unaltered in the adult. The most important changes 
concern the ganglion c.g. ; this, which at stages K and L isa 
large prominent swelling (fig. 10, ey.), in the later stages 
becomes far less conspicuous, and the ganglionic cells, instead 
of being concentrated at one spot, occur in small scattered 
patches at different parts of the nerve. This change is seen 
commencing at stage N (fig. 11, ¢.g.), where the ganglion has 
divided into two main portions, one part retaining its original 
position, whilst the other becomes connected with the nerve J. 
at some little distance from the third nerve; at stage o-p 
(figs. 14 and 15) ganglion cells appear to be constantly present 
at two well-marked points in the course of the third, (1) where 
the nerve JV. is given off, and (2) immediately above the rectus 
superior. 
At stages K and t (fig. 10) the angle between the nerves N.c. 
and J. is very considerable, and this increases in the later stages 
so much that at stage N (fig. 11) the two nerves are almost at right 
angles to one another; at stages later than this the nerve WV. 
is much more difficult to define, whilst owing to the close 
