478 LANDACRE AND McLELLAN 
Coghill and Norris). This ganglion resembles closely in form 
and position the lateralis X of Ameiurus and Lepidosteus in simi- 
lar stages of development. It extends considerably posterior to 
any other ganglion and the nerve arises at the posterior atten- 
uated extremity as in those types. 
(c) The ventral lateralis X is the third of these ganglia. It is 
ventral to dorsal lateralis X in young embryos, but later, owing 
to the flattening of the head, becomes more lateral in position. It 
lies lateral to visceralis X? in young embryos and later assumes 
a more dorsal position with reference to visceralis X2 and also ~ 
becomes more closely fused with the dorsal lateralis X. It gives 
rise to one nerve which emerges from the ventral apex of the gan- 
glion (the most anterior lateral line ramus (5) of Strong’s plot 
and the ramus lateralis ventralis of Coghill and Norris). 
The presence of two lateral line ganglia on X suggests at once 
a homology with the condition in VII where there are two lateral 
line ganglia also. As to the distinctness of this ganglion up to 
and beyond the 10 mm. stage there can be no doubt. Nor is it 
doubtful that it is a lateral line ganglion. The size of its cells, 
their heavy pigmentation. and the isolation of the ganglion settles 
both these doubts. As to the homology with ventro-lateral VII, 
we are not willing to go farther at present than to gives it a name 
signifying its composition and position in the X complex. It 
gives rise to the same component as ventro-lateral VII, it occupies 
the same relative position, 1.e., lateral to a visceral ganglion and in 
the distal portion of the complex as does ventro-lateral VII. Its 
nerve also runs out in conjunction with a branchial nerve. If it 
should prove to have a similar mode of origin to that ganglion 
there would seem to be no objection to homologizing them. No 
other fish or amphibian studied so far as we know has a distinct 
ventral lateralis ganglion. An examination of the reconstruc- 
tions of Coghill (02) and of Norris (08) indicates that probably 
the same condition will be found in Urodeles, since the lateral line 
cells extend well down ventrally toward the origin of the ramus 
lateralis ventralis in both cases. 
4. The jugular, or general somatic X, as in other Ichthyopsida 
above the Cyclostomes, is the only representative of its type in 
