CRUSTACEANS. 



311 



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 Laemodipoda, 

 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 

 243 whai c l r is 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. 244 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 



