BARNACLES. 



225 



angles from the surface. Now the ."fingers," expanded 

 like a fan, and curved like a half-open hand, make the 

 framework of a net, while the transverse bristles, those 

 of each " finger " meeting and interlocking with those of 

 the next, constitute a series of meshes occupying the inter- 

 stices, and the whole, cast out and withdrawn, form a most 

 efficient strainer of the water, arresting every minute 

 atom, living or dead, which, being then passed down to 

 the mouth at the bottom of the net, is either swallowed 

 or rejected, according as it is fit for food or worthless. 



The Barnacle, whether sessile or stalked, passes through 

 a series of metamorphoses, which shew that, although its 

 appearance and instincts when adult have a great resem- 

 blance to those of the Mollusca, its affinities are truly 

 with the Crustacea. It begins life in a form exactly like 

 that of a young Entomostracous Crustacean, with a broad 

 carapace, a single eye, two pairs of antennae, three pairs 

 of jointed, branched, and well-bristled legs, and a forked 

 tail. It casts off its skin twice, undergoing, especially 

 at the second moult, a considerable change of figure. At 

 the third moult it has assumed almost the form of a 

 Cypris or Cy there, being enclosed in a bivalve shell, in which 

 the front of the head, with the antennae, is greatly de- 

 veloped, equalling in bulk all the rest of the body. The 

 single eye has become two, which are very large, and 

 attached to the outer arms of two bent processes like the 

 letters U U, which are seen within the thorax. 



In this stage the little animal searches about for some 

 suitable spot for permanent residence ; a ship's bottom, a 

 piece of floating timber, the back of a whale or turtle, or 

 the solid rock. When its selection is made, the two antenn£e, 



