PLATE 1 
A flat reconstruction of the brain, sense organs and sensory components of 
V, VII, VIII, IX and X cerebral ganglia of a 10 mm. embryo of Lepidosteus osseus. 
General cutaneous ganglia are indicated by horizontal shading and this compon- 
ent is found at this stage in the profundus (trigeminus I) and the Gasserian gan- 
glion (trigeminus II). The jugular ganglion of the X is not present at this stage; 
when it becomes organized it lies on the root of the X near the entrance of the root 
into the brain. 
The special cutaneous ganglia are indicated by cross hatching and are found in 
the VII (dorso-lateral and ventro-lateral lateralis ganglia of the VII), in the VIII, 
IX and X. 
General visceral ganglia are indicated by vertical lines and are found in the 
VII (geniculate), IX (petrosal), and X (nodosal). 
The special visceral ganglia are indicated by stipple and are found in the VII, 
IX and X, there being only two of the four epibranchial ganglia of the X found at 
this stage. Aside from the hyomandibular nerve, all the nerve trunks are pure, 
i.e., contain only one component. The absence of the last two branchial ganglia 
and the lack of fusion in nerve. trunks, which takes place later, are the chief dif- 
ferences between this embryo and older stages. 
The scale at the side of the figure indicates the serial numbers of the sections 
from which the reconstruction was made. 
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