462 LANDACRE AND McLELLAN 
vagal complex of ganglia that are not as clear as could be desired 
in Strong’s work and do not show the resemblance to the type 
of composition of ganglia usually found in the Ichthyopsida. 
Since the V and VII complex conforms so closely to the type 
for Ichthyopsida, one would naturally expect the [IX and X com- 
plex to be equally true to type, because the V and VII is usually 
the more highly developed and almost invariably has its ganglionic 
components more closely fused than IX + X in any given stage. 
An examination of embryos younger than that plotted by Strong 
shows the [IX + X ganglionic complex to be really much more 
typical and not so highly fused as shown on Strong’s plot, thus 
enabling one to make a much more detailed analysis. 
MATERIAL 
The series of embryos from which two were selected for plotting 
consists of eighty-six stages taken from one lot of eggs of Rana 
pipiens. The first fifty-three stages were taken at intervals of 
two hours beginning six hours after laying. From the fifty- 
third stage up to the eighty-fifth the intervals were less regular, 
ranging from one and three-quarter hours to nine hours, the 
average being less than five hours. 
Out of this series number seventy-two, 8 mm. in length (1714 
hours old) and number eighty-six were chosen for plotting. Num- 
ber eighty-six is 135 hours older than number seventy-two, being 
3064 hours old and 10 mm. in length. In addition to this series, 
a 25 mm. tadpole of Rana pipiens was studied and also a 35 mm. 
series kindly loaned by Professor Herrick. Neither of these last 
two were plotted, but they were carefully compared with the 8 
mm. and 10 mm. embryos plotted. Stage 35 mm. seems to be 
similar in all essential respects to Strong’s plot. 
THE TRIGEMINO-FACIAL COMPLEX 
In the trigemino-facial complex (fig. 1) one point only needs 
to be emphasized, namely, the distinctness of the profundus gan- 
glion. This ganglion, which in earlier stages is much more isolated 
than in the 8 mm. embryo, though not entirely distinct, occupies 
