CONSTRUCTION OF SHELLS. il 
families of Turbo, of Voluta, of Conus, and of Cyprea, 
some of which, either exhibit the glowing colours of 
the rainbow, or the tints of the finest tulips, or else 
resemble little marine lamps, suspended in the cre- 
vices of dark rocks ; while a considerable number 
appear invested with silver armour, as they walk 
under the spreading shades of the madrepore. 
Such, on the contrary, as seldom move from their 
places of abode, or may easily be discovered, are 
uniformly of the same colour as the sites which 
they occupy, or the party-coloured stones, or sea- 
weeds to which they cling. We may adduce, as 
a familiar example, the common Snail, which is 
searcely to be distinguished from the ground over 
which it creeps; or the still more helpless Limpet, 
that adheres to the surface of the rocks by means of 
a vacuum, which it produces at pleasure, like the 
inhabitants of the little cones which are seen on the 
broad leaves of the pear-tree. 
The same extraordinary compensation with respect 
to colour is also obvious in the Oysters of the Red 
Sea, which hide themselves in the fissures of the 
rocks; in the Muscles, that ride at anchor in the 
shallows of the sea-shore; in the Fin-shells, which 
moor their fragile barks to the pebbles by means of 
silken cords; in the silver-tinted Anomiz, or antique 
lamps, which attach themselves to floating tufts of 
