300 CIRRHIPODA. 



shell, near the place where it is fixed to the stalk, and 

 its tail at the upper extremity. The tail is not unlike 

 that of a Crustacean, and is bordered on each side with 

 six lobes (representing the segments of the articulate 

 body of that class), each of which supports a pair of 

 long, ciliated arms, or cirrhi, the whole resembling a 

 plume of purple feathers. These cirrhi, when the ani- 

 mal is alive, are constantly in motion, projecting out- 

 ward, and expanding into an oval, concave net, then 

 retracting inwards, and closing upon whatever may have 

 come within their reach. They are so placed that any 

 small matter which becomes entangled within them can 

 rarely escape, and finds a ready passage to the mouth. 

 Very similar to the Barnacle is the animal of the Bala- 

 nus, whose shells cover, in scurfy patches, the surface of 

 exposed rocks, as well as drift-wood, or any other sub- 

 merged substance. These shells are usually white, shaped 

 like truncated cones, and composed of several ribbed 

 pieces closely fitted together, with an aperture at top, 

 closed by an operculum, and within this house the crea- 

 ture is lodged. Like the Barnacle, it puts out its arms 

 in search of food, though to a less extent. There are 

 many varieties of both kinds ; that is to say, of the 

 sessile and stalked Cirrhipoda. Some of the former of 

 large size, form a lodgment in the coats of Whales ; 

 others lodge themselves in Corals or Sponges. The 

 habits of the race are very uniform. Once fixed, they 

 remain so during their lives, taking chance for subsist- 

 ence. In an early stage, however, they are free to move 

 from place to place, and are lively little beings, swimming 

 about with the speed of Water-fleas (Daphni<x), which 



