46 F, L. LANDACRE 
tribute cells to the neural crest portions of the corresponding 
ganglia. In other types where the placodes are less prominent 
an actual contribution of cells to the neural crest portion of the 
corresponding ganglia has not been shown to take place, but a 
contact is formed between the neural crest ganglia and the epi- 
dermis in all cases. In view of the reduced character of the gusta- 
tory system in many forms as compared with the fishes, it is not 
surprising that the actual contribution of cells by the epibran- 
chial placode should not be large and might take place during 
the period of contact and still be difficult to demonstrate. There 
seems to be no other adequate explanation for the formation of 
this contact between the neural crest ganglia and the ectoderm in 
such types that would harmonize with the known conditions in 
Ameliurus and Lepidosteus. 
In all types epibranchial placodes occur on those nerves and 
those only, VII, IX and X, which contain gustatory fibers. 
Whenever, as is usually the case among the Ichthyopsida, the 
ganglia of these nerves are complex, containing lateralis, cutaneous 
and visceral components, the placodal cells join only the visceral 
ganglia, never the lateralis or general cutaneous ganglia. These 
visceral ganglia give rise to fibers supplying general visceral sur- 
faces and taste buds only. In Ameiurus and Lepidosteus the 
various components of the ganglia are so distinct in the embryos 
that this conclusion can not be doubted and the problem resolves 
itself into the effort to differentiate special visceral or gustatory, 
and general visceral ganglia. Ganglia such as the profundus and 
Gasserian which do not contain visceral fibers of either type and 
have no epibranchial placodes, can be eliminated. With equal 
certainty we can eliminate all lateralis and general cutaneous 
ganglia in VII, [X and X, since they give rise to no visceral fibers 
of either type and have no epibranchial placodes. 
An examination of the visceral ganglia of Ameiurus shows that 
the VII ganglion, which in the adult supplies a large number of 
taste buds, has a large placode, while the last branchial ganglion 
of the X which supplies in most types a limited number of taste 
buds, has a small placode. The visceral portion of the [X seems 
to be exclusively placodal in origin and seems in the adult to give 
