CRUSTACEANS. Silk 
a larger shell, and it is amusing to see one trying one 
shell after another to find one which will fit. 
531. In the order of Lemodipoda, 
or jaw-footed Crustacea, is the Whale 
Louse, Figure 243, which clings by its 
strong claws to the body of the Whale. 
So completely is the Whale sometimes 
covered by these parasites, that a white 
ee 4 6.4, § Coloris given to its skin, which can be 
Louse. seen at some distance. 
532. The order of Cirrhipoda, or tufted-footed Crusta- 
cea, contains the Barnacles, Fig. 244, and their allies. The 
Fig. 2-4.—Barnacles. 
Barnacle looks like a mussel-shell fixed to a long stem; 
but, on examination, it is found that the shell consists 
of five pieces, and through the opening project seven 
pairs of arms or cirrhi. Two of these are of considerable 
size, and have suckers on the end, by which they can 
hold on to any thing. The other six pairs are fringed 
with cilia, or hair-like filaments, which, by their contin- 
ual motion, produce currents in the water. This serves 
both to bring minute animals, constituting the food of 
the Barnacle, within the reach of the arms, and to move 
the water over the gills. The animal has jaws which 
take and masticate the food brought to it by the arms. 
In Fig. 245 (p. 312) is a Barnacle with the shell partly 
removed, to show all the parts of the animal. It is al- 
ways found adhering by the stem to floating wood or 
