184 Proceedings of Royal Society of Edinburgh, [march 5, 
the inner palps, but, as a rule, is in the opposite direction. It 
sometimes changes, especially after a short halt, and is accom- 
panied by a corresponding change in the movement of the cilia, 
as described in the gill (Purkinje and Yalentiu, Physiologic). The 
motion is longer continued and more rapid than in the inner 
palps. 
Left . — The left was observed for twenty rounds moving to the 
right with great regularity. The average was minutes to the 
round, the slowest being 9|- minutes, and the quickest 6 minutes. 
It commenced at the rate of 6 minutes per round, and with a steady 
pace, varying from 6 to 9 minutes, the 20th round was performed 
in 7|- minutes. The movement still continued when I ceased 
recording. 
Right . — The right was observed continuously for 50 rounds, and 
for given periods of time the rate was pretty constant : the general 
average was 5 minutes to the round ; the slow^est record was at the 
commencement, with 25 minutes to the round; and the quickest 
was 2 minutes. The partial average for the twenty best continuous 
rounds, from the 13th to 32nd inclusive, was 3 minutes; and the 
middle round of the whole (25th) was 2 minutes. The palp was 
going at the rate of 4 minutes to the round when I left off record- 
ing, and the 51st round took 5| minutes. 
Both left and right continued to move for some time afterwards, 
as I observed them for 25 minutes, before leaving them for the 
niglit, rotating as usual. 
General Remarks . — The left outer moved a little to the left at 
first, without turning round. Then it began to turn very, very 
slowly, but there was no elevation of the tip, only expansion and 
contraction of it. After an hour and a half had elapsed without 
the round being completed, I pricked it a little, and it drew itself 
up. Shortly after it began to elevate its tip and turn back, reach- 
ing its original position 1 hour 46 minutes from the start. It 
immediately began to turn to the right or outward^ and in 6 
minutes had completed its first round. I note this partly to explain 
the phenomenally rapid first round, and partly to show that parts 
may not behave normally for a little after they have been detached, 
and until they have become adapted to a free, instead of a fixed, 
condition of existence. 
