2/6 CRUSTACEA, ECHINODERMS, ETC. 



search of fresh oxygen and food. When the stalked 

 species (so called from the flexible muscular tube, 

 often of great length, to the free end of which the 

 body of the barnacle is attached) have ceased lead- 

 ing a free-swimming life, they in reality settle down 



Fig. 207. 



Fig. 208. 



Balanus hameri. 



Scalpellum vulgare. 



by their heads. The feet then produce the feathery 

 gills, and are hereafter employed in sweeping the 

 water to and fro, instead of swimming or walking. 

 In reality there is not much modification here, for 

 if the legs of a lobster be plucked off sharply, there 



