LIMPETS. 155 
These habits were first made known by Mr. 
Lukis, a naturalist of Guernsey, to whom we are 
indebted for other interesting notes on the economy 
of animals. “The locomotion of the Limpet,” he 
observes, ‘may be ascertained by marking one 
individual to avoid mistake, and then observe its 
cautious roaming and regular return to its favourite 
place of rest, where the shell will be found exactly 
to correspond with the surface of the rock to which 
it is attached. Here it will rest or sleep, and only 
relax its strong adhesion to the rock, when the 
muscular fibre becomes exhausted by long con- 
traction, in which state a sudden blow, horizontally 
given, will easily displace it. A fact known to the 
fishermen and poor, who use them for food, is, that 
they are more easily collected in the night time 
than in the day. May not this be the period of 
roaming for food as well as when covered by the 
tide ? 
“The march of the limpet is slow and formal ; 
and whenever the cupping process is renewed, the 
posterior end of the shell is brought in contact 
with the rock, which is of a soft nature, and will 
receive the impressions of its denticulations. The 
track of an individual placed under surveillance 
was thus made visible over a space of several 
yards, possessing the same regularity and dis- 
position, and was further remarkable for the con- 
stant revolution on its left. 
“The tracks of the limpet on granite and other 
hard rocks, present, at first sight, the same appear- 
ances; but, on a closer examination, they are 
found to differ. When first observed in 1829, a 
large portion of a fine-grained sienitic rock was 
traced over by these shells; the remainder was 
