118 THE HALL OF SHELLS. 
“Tn their first form these little castle hold- 
ers, but dancing atoms, have one big black eye, 
three pairs of legs, and on the forehead a pair 
of flexible horns. If we did not know the end 
we should say a mistake had been made in 
their legs, which seem to grow more and more 
unfit for use either for land or water. ‘As- 
cending the scale,’ the body with its frmged 
legs, to which are added two pair more, is now 
inclosed in a tiny two-valved shell lke a mus- 
sel. Its one eye becomes two, its head and 
antenne increase in size, and it now prepares 
to make the most wonderful change of all. It 
‘stands on its head’ literally and fastens itself 
head downward to the rocks by means of a 
cement itself secretes. Its bivalve shell is no 
longer needed, its shield becomes the beginning 
of its castle walls, and its group of legs become 
tentacles which wave gracefully backward and 
look lke delicate curls of hair. It is these 
which give the name Cirripeda to this group, 
cirrus meaning a lock of hair and pedes a foot. 
“They now are true barnacles, and their 
castles by the sea are like turrets crowding one 
upon another. 
“ All barnacles are not the same kind, and 
their turrets are not all upon the rocks. Many 
are attached to pieces of wood, hulls of ships, 
