256 BARNACLES. 
that two of them had thrown off their exuvie, and, 
wonderful to say, were firmly adhering to the bottom of 
the vessel, and changed to young barnacles. In this stage 
the sutures between the valves of the shell and of the 
operculum were visible, and the movements of the arms 
of the animal within, although these last were not com- 
pletely developed: the eyes also were still perceptible, 
although the principal part of the colouring-matter ap- 
peared to have been thrown off with the exuvie. On the 
1oth another individual was seen in the act of throwing 
off its shell, and attaching itself as the others to the bot- 
tom of the glass. It only remains to add, that as the 
secretion of the calcareous matter goes on in the compart- 
ments destined for the valves of the shelly covering, the 
eyes gradually disappear, from the increasing opacity 
thence produced, and the visual ray is extinguished for 
the remainder of the animal’s life ; the arms at the same 
time acquire their usual ciliated appearance. Thus, then, 
an animal originally natatory and locomotive, and provided 
with a distinct organ of sight, becomes permanently and 
immovably fixed, and its optic apparatus obliterated ; and 
furnishes not only a new and important physiological fact, 
but is the only instance in nature of so extraordinary a 
metamorphosis. 
We have been thus led to dilate upon barnacles in con- 
nection with Shakespeare’s allusion to them, at somewhat 
greater length than we should otherwise have done, on 
account of the interest which attaches to the old story, 
