32 JOHNS HOPKINS UNIVERSITY MORPHOLOGICAL MONOGRAPHS. 
The pedalia could be made to contract by giving the subumbrella 
a prick,—generally a rather severe one was necessary. The upper 
part of the subumbrella seems not so sensitive as the lower part and 
the proboscis, and the base of the stomach did not give any reflex 
at all (two specimens). One of the two could be made to give the 
reflex only with much difficulty. This was a very lively one. It 
would even stand severe pricks on the nerve, or even through the 
region of the sensory clubs, without contracting the pedalia or stop- 
ping pulsations. 
Cutting the frenula seemed not to affect the ability to swim well. 
Cutting in this region brings about the reflex of the pedalia. 
In the preceding fish the velaritwm was cut away wholly in some 
places, in other places it was left only as ragged strips. The pedalia 
became very strongly contracted and the tentacles were brought inside 
the bell. Pulsations that seemed strong produced much less progress 
than with the velarium intact. [Repeated.] 
30. One with the whole margin cut off still gave pulsations. Upon 
the removal of the region of the radial ganglia, however, pulsations 
were seen no more. 
The velartum in the above continued to give twitchings. The four 
pedalia were cut off with plenty of the tissue at their bases to insure 
the removal of interradial ganglia, and twitchings of the velarium with 
irregular contractions continued. No full contraction all around the 
velarium was noticed. When all the tissue was trimmed off as nearly 
as possible down to the velarium, the latter still gave twitchings and 
irregular contractions as before,—even more so as if excited by the 
operation. The power of originating contractions evidently resides in 
the velarium or in the ganglion cells of the frenula just as it does in 
the proboscis and the floor of the stomach. 
Small pieces cut from between the pedalium corners and _ the 
frenula, so as to have tissue on them from neither, could contract 
by themselves. (See also for Pedalia, Experiments 15, 23, 41b, 
Velarium 18, 41c.) 
Tentacles.—31. A cut-off tentacle can contract by itself, sometimes 
with squirming contractions. A prick at either end can produce a 
forcible contraction. A slight prick at the distal end may produce a 
local contraction. The proximal end is more sensitive, but this differ- 
ence is not very marked. One with only the tentacles removed 
seemed to be a little less able to guide itself well. 
