SHORES OF THE CLYDE AND FIRTH. 
51 
forest of long flesh coloured arms protrude, and, like the spines, 
wave about in all directions, and are furnished on the tip 
with a cup-like sucker, by which they lay hold of objects and 
use in locomotion. The united strength of the vacuum of 
these suckers is very great. I have seen them stand the 
lash of tremendous waves, and ere they relax their hold the 
arms will be torn from the cups, which will still retain in 
their severed state the hold of the object they are adhered to. 
If our captive is hungry, by dropping into the bottle a 
very small crab, we will have a good chance of witnessing 
his mode of progression ; or, if he shies at the crab, the little 
chiton, a favourite bite, will entice him. Rolling himself 
into a ball, as the cunning little chiton always does when 
captured, we drop him to the bottom. The moment master 
urchin gets his eyes upon him, a downward movement is 
begun ; and how interesting it is to watch the slow, almost 
imperceptible glide of the creature's motion. First we see 
the arms at the lower edge relax their hold, then, reaching 
further down, adhere again, while those immediately above 
follow suit ; and so on to the top. Such is the order of 
progression, and if the pace is slow it is sure, and there is 
never no stumbling; nevertheless it is amazing how speedily 
the bottom is reached, where the chiton, still in a doubtful 
state regarding his own safety, deems himself yet more 
secure within the folds of his shelly armour. 
Across the bottom a straight track is made until the 
arms come within grasping length of the victim, which is 
quickly seized by the inexorable suckers, and a retreat is 
then made to the side, dragging the poor helpless chiton 
along without a struggle. While the urchin is travelling, 
the position of the captive remains unchanged, but the 
instant the side is reached, a movement towards the mouth 
begins, and when that point is gained the pressure of the 
