46 F. L. LANDACRE 
the posterior twig of lateralis X, may belong to the main body 
line. It les much more ventral in position than those inner- 
vated by the anterior twig. 
27. THE GANGLION LATERALE X, 
The lateralis ganglion (figs. 1 and 8, G.L.X,) associated with 
the second branchial ganglion of X resembles that on the first 
branchial ganglion of X in its relations to other members of 
the complex. It is, however, longer and placed parallel to the 
long axis of the body. It is not so definitely confined to its 
branchial ganglion as that on X,, since its posterior end is con- 
tinuous with lateralis X;. Its proximal and anterior end is 
mesial to the somatic muscle primordium and is in contact with 
jugular X, to which it hes ventral. Throughout its whole 
course it lies lateral to the fibrous motor and sensory root of the 
remaining visceral ganglia of X. Its posterior and distal end 
lies lateral to the somatic muscle primordium. On its extreme 
distal and posterior end its cells are continuous with those of 
lateralis X; and throughout the posterior half of its extent it is 
in contact with the visceral ganglion of branchial X;, to which 
it lies dorsal. Throughout the proximal portion of this contact 
the two ganglia are closely fused and, owing to the similarity in 
size of their cells, indistinguishable. However, throughout the 
greater portion of the contact the combined ganglia are indented 
both on the mesial and on their lateral surfaces, indicating the 
line of separation between them. Near its posterior end this 
ganglion gives rise to the first ramus lateralis X. 
28. FIRST RAMUS LATERALIS X 
Owing to the position of the lateral line primordium inner- 
vated by the lateral line ramus arising from this ganglion, it is 
identified as the first primordium of the main body line and its 
nerve as the first lateral line ramus of X, rather than as a homo- 
logue of the more anterior ramus supratemporalis X. The 
study of this nerve in much older material, however, may show 
it to be homologous to a supratemporal ramus. 
