Almost every one is acquainted with at least one kind of the Barnacle shells which were supposed to enclose the embryo of a goose, namely the small white conical hillocks which are found, in tens of thousands, adhering to stones, rocks, and old timber such as the piles of piers, and may be seen affixed to the shells of oysters and mussels in any fishmonger's shop. The little animals which secrete and inhabit these shells belong to a sub-class and order of the Crustacea, called the Cirrhopoda, because their feet (poda), which in the crab and lobster terminate in claws, are modified into tufts of curled hairs (cirri), or feathers. When the animal is alive and active under water, a crater may be seen to open on the summit of the little shelly mountain, and, as if from the mouth of a miniature volcano, there issue from this aperture, from between two inner shells, the cirri in the form of a feathery hand, which clutches at the water within its reach, and is then quickly retracted within the shell. During this movement the hair-fringed fingers have filtered from the water and conveyed towards the mouth within the shell, for their owner's nutriment, some minute solid particles or animalcules, and this action of the casting-net alternately shot forth and retracted continues for hours incessantly, as the water flows over its resting-place. The animal can live for a long time out of water, and in some situations thus passes half its life. Under such circumstances, the shells, containing a reserve of moisture, remain firmly closed until the return of the tide brings a fresh supply of water and food. These are the "acorn-barnacles," the balani, commonly known in some localities as "chitters."
Barnacles of another kind are those furnished with a long stem, or peduncle, which Sir Robert Moray described as "round, hollow, and creased, and not unlike the wind-pipe of a chicken." The stem has, in fact, the ringed formation of the annelids, or worms. The shelly valves are thin, flat, and in shape somewhat like a mitre. They are composed of five pieces, two on each side, and one, a kind of rounded keel along the back of the valves, by which these are united. The shells are delicately tinted with lavender or pale blue varied with white, and the edges are frequently of a bright chrome yellow or orange colour.
It is not an uncommon occurrence for a large plank entirely covered with these "necked barnacles" to be found floating at sea and brought ashore for exhibition at some watering-place; and I have more than once sent portions of such planks to the Aquaria at Brighton, and the Crystal Palace.
It is most interesting to watch a dense mass of living cirripedes so closely packed together that not a speck of the surface of the wood is left uncovered by them; their fleshy stalks overhanging each other, and often attached in clusters to those of some larger individuals; their plumose casting-nets ever gathering in the food that comes within their reach, and carrying towards the mouth any solid particles suitable for their sustenance. How much of insoluble matter barnacles will eliminate from the water is shown by the rapidity with which they will render turbid sea water clear and transparent. The most common species of these "necked barnacles" bears the name of "Lepas anatifera," "the duck-bearing Lepas." It was so entitled by Linnæus, in recognition of its having been connected with the fable, which, of course, met with no credit from him.
Fig. 39 represents the figure-head of a ship, partly covered with barnacles, which was picked up about thirty miles off Lowestoft on the 22nd of October, 1857. It was described in the Illustrated London News, and the proprietors of that paper have kindly given me a copy of the block from which its portrait was printed.
Others of the barnacles affix themselves to the bottoms of ships, or parasitically upon whales and sharks, and those of the latter kind often burrow deeply into the skin of their host. Fig. 40 is a portrait of a Coronula diadema taken from the nose of a whale stranded at Kintradwell, in the north of Scotland, in 1866, and sent to the late Mr. Frank Buckland. Growing on this Coronula are three of the curious eared barnacles, Conchoderma aurita; the Lepas aurita of Linnæus. The species of the whale from which these Barnacles were taken was not mentioned, but it was probably the "hunch-backed" whale, Megaptera longimana, which is generally infested with this Coronula. This very illustrative specimen was, and I hope still is, in Mr. Buckland's Museum at South Kensington. It was described by him in Land and Water, of May 19th, 1866, and I am indebted to the proprietors of that paper for the accompanying portrait of it.
