BARNACLE. 161 



furnished with jointed limbs, much resembling 

 a young shrimp or crab, and swimming freely 

 through the water with a succession of bounds. 

 When first discovered, the young balani were 

 thought to be veritable crustaceans ; but after 

 careful observation they were seen to affix them- 

 selves to the sides of the vessel in which they 

 were placed, and straightway to change their 

 roving life for an existence of settled quiet. 

 Similar strange developments take place in many 

 marine animals, but there will not be sufficient 

 space for their discussion. 



The balanus has a very near relative going 

 by the popular name of Ship-barnacle, and the 



BARNACLE. 



scientific title of Pentalasmis anatifera, the latter 

 title signifying "the five-plated goose-bearer." 

 It is called Pentalasmis, or five-plated, because 

 its shell is composed of five distinct portions, 



M 



