THE BARNACLES. 245 
shield like that of many of the lower crustaceans. After going 
through a series of metamorphoses, these larvee, tired of a roam- 
ing life, attach themselves by their head, a portion of which be- 
comes excessively clongated into the “ peduncle ” of the Barnacles, 
whilst in the Balani 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 cirri, 
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 anima] 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 aérate 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 Coronule 
settle so profusely on the skin of the Greenland whale as often to 
hide: the colour of its skin, while the Tubicinelle 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 of Balanus 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 
s 
