230 HALF AN HOUR WITH CRUSTACEA. 



seen old prints in which the artist has endeavoured 

 to illustrate this idea. Attention has been drawn 

 to the law of " alternation of generations " in many 

 marine animals, so that we are prepared beforehand 

 not to be greatly surprised at anything marvel- 

 lous ; but this ancient belief transcends all we have 

 yet told ! The stalk of this species is from eight 

 inches to a foot in length, and is tough and leathery, 

 having muscles running through it which contort it 

 and cause the whole organism to wave to and fro in 

 the water like a tall tree in a high wind. This 

 species it is which, in warmer seas, so greatly in- 

 fests ships' bottoms as to render navigation difficult. 

 When that part of the animal enclosed within the 

 valves is watched, there will be seen to emerge a 

 hand-like member, the fingers of which are beauti- 

 fully feathered. It is this striking resemblance to 

 a feather which perhaps first suggested the fable 

 about its being a transformed goose. The colour 

 of the feathery fingers is purplish-black, and about 

 three-quarters of an inch in length. When put out, 

 they snap at and curl round any organism that may 

 serve them as food, and immediately jerk it to the 

 mouth, closing their valves after them. The " Acorn- 

 shells," or sessile barnacles (Balanus balanoides), are 

 abundant everywhere perhaps a trifle too much 

 so, you will be inclined to think, when you find 

 that their sharp edges have clean cut through your 

 wetted boots as you were zoologising among the 

 rock-pools at low water ! You notice that each 



