THE BARNACLES. 245 



shield like that of many of the lower crustaceans. After going 

 through a series of metamorphoses, these larva, tired of a roam- 

 ing life, attach themselves by their head, a portion of which be- 

 comes excessively elongated into the " peduncle " of the Barnacles, 

 whilst in the Ealani or acorn-shells it expands into a broad 

 disk of adhesion. The multivalve shell is gradually formed, 

 the eyes are cast away as being no longer needed, and the now 

 useless feet are replaced by six pairs of extremely useful cirrhi f 

 long, slender, many-jointed, tendril-like appendages fringed with 

 delicate filaments and covered with vibratile cilia. These cirrhi, 

 which resemble a plume of purple feathers, and from whose 

 peculiar character the name of the group, Cirrhipoda, is de- 

 rived, are constantly in motion as long as they are bathed in 

 water, projecting outwards and expanding into an oval concave 

 net, then retracting inwards, and closing upon whatever may 

 have come within their reach. They are so judiciously placed 

 that any small animal which becomes entangled within them 

 can rarely escape, and is at once conveyed to the mouth. The 

 currents produced in the water by their perpetual activity 

 serve also to aerate the blood, so that these delicate organs act 

 both as gills and as prehensile arms. In spite of their sessile 

 condition, the Cirrhipeds have not been left without protection 

 against hostile attacks, for at the approach of danger they shrink 

 within their shell, and close its orifice against a host of hungry 

 intruders. 



Their various families are widely spread over the seas. It is 

 well known that the barnacles frequently attach themselves in 

 such vast numbers to ships' bottoms as materially to obstruct 

 their way, and the acorn- shells often line the coasts for miles 

 and miles with their large white scurfy patches. The Coronulse 

 settle so profusely on the skin of the Greenland whale as often to 

 hide the colour of its skin, while the Tubicinellae exclusively 

 occur on the huge cetaceans of the South Sea. Some of the 

 larger sea-acorns are highly esteemed as articles of food. The-. 

 Chinese, after eating the animal ofBalanus tintinnabulum with 

 salt and vinegar, use the shell, which is about two or three 

 inches high and an inch in diameter, as a lamp, and the flesh of 

 Balanus psittacus on the southern parts of the South American 

 coast is said to equal in richness and delicacy that of the crab. 



While the Cirrhipeds grasp their prey as in a living net, the 

 Siphonostomata lead a parasitic life chiefly upon fishes, sucking 



