GANGLIA AND NERVES OF SQUALUS 47 
This nerve (figs. 1, 9, 10 and 11, R.L.X.1) arises near the 
posterior end of ganglion laterale X, accompanied by the nerve 
identified as ramus auricularis. Immediately after its exit from 
the ganglion it gives off a small twig to the lateral line primor- 
dium. Posterior to this twig at least two more twigs are given 
off to the same primordium which extends caudad to the level 
of the first spinal ganglion. Posterior to this point the ter- 
minal twig of this nerve can be followed, but it does not end 
on a lateral line primordium. There is nothing in its relation 
to the ectoderm, other than the absence of lateral line primordia 
posterior to this point, by which to identify it. The extremely 
immature condition of the general cutaneous rami of X make 
it difficult to be certain of its identity. The only other possi- 
bility apparently is that it might be a visceral sensory twig 
destined for terminal buds on the ectoderm. This can be de- 
termined, however, only on older material and it is indicated on 
the plot as a lateral line nerve. 
29 THE GANGLION LATERALE X; 
This ganglion (figs. 1, 9, 10 and 11, G.L.X;) shows many of 
the characteristics of lateralis X,. It is longer and placed 
slightly more diagonally in the body with its anterior end more 
dorsal than its posterior end. The ganglion is round in trans- 
verse section and lies throughout its whole extent lateral to the 
primordium of the somatic musculature. 
At its anterior and proximal end it is in contact and con- 
tinuous with lateralis X» on its dorsal surface, while on its ven- 
tral surface it is contact for a short distance with the visceral 
ganglion of X». The remainder of its dorsal surface is free, 
but on its ventral surface it is in contact first with the visceral 
ganglion of X;, and at its posterior end for a short distance with 
the visceral ganglion of X,. Its ganglion cells are much larger 
than the visceral ganglion cells and their identification is easy. 
The fibrous motor and sensory roots of the complex posterior to 
this point lie on the ventral portion of lateralis X; instead of on 
the mesial surface, as in the case of the two preceding lateral line 
ganglia. 
