Page:EB1911 - Volume 28.djvu/827

Rh took name from a holy well, of high repute for curative powers, over which an oratory was erected early in the 12th century, attached to the priory of St John of Jerusalem in Clerkenwell.  WOOD-LOUSE, a name commonly applied to certain terrestrial Crustacea of the order Isopoda (see ), which are found in damp places, under stones or dead leaves, or among decaying wood. They form the tribe Oniscoidea and are distinguished from all other Isopoda by their habit of living on land and breathing air, and by a number of structural characters, such as the small size of the antennules and the absence of the mandibular pulp. As in most Isopods, the body is flattened, and consists of a head, seven thoracic segments which are always free, and six abdominal segments which may be free or fused. The “telson” is not separated from the last abdominal segment The head bears a pair of sessile compound eyes as well as the minute antennules and the longer antennae. Each of the seven thoracic segments carries a pair of walking legs. The appendages of the abdomen (with the exception of the last pair) are flat membranous plates and serve as organs of respiration. In many cases their outer branches have small cavities opening to the outside by slit-like apertures, and giving rise internally to a system of ramifying tubules filled with air. From their similarity to the air tubes or tracheae of insects and other air-breathing Arthropods these tubules are known as “pseudotracheae.”

The female wood-louse carries her eggs, after they are extruded from the body, in a pouch or “marsupium” which covers the under surface of the thorax and is formed by overlapping plates attached to the bases of the first five pairs of legs. The young, on leaving this pouch, are like miniature adults except that they are without the last pair of legs. Like all Arthropoda, they cast their skin frequently during growth. As a rule the skin of the hinder half of the body is moulted some days before that of the front half, so that individuals in process of moulting have a very peculiar appearance.

Some twenty-four species of wood-lice occur in the British Islands. Some, like the very common slaty-blue Porcellio scaber, are practically Common Wood-louse, Oniscus asellus. cosmopolitan in their distribution, having been transported, probably by the unconscious agency of man, to nearly all parts of the globe. Equally common is the brown, yellow-spotted Oniscus asellus. Armadillidium vulgare belongs to a group which have the power of rolling themselves up into a ball when touched and resembles the millipede Glomeris. It was formerly employed in popular medicine as a ready-made pill. The largest British species is Ligia oceanica, which frequents the sea-shore, just above high-water mark. In many points of structure, for instance in the long, many-jointed antennae, it is intermediate, as it is in habits, between the truly terrestrial forms and their marine allies. Finally, one of the most interesting species is the little, blind, and colorless Platyarthrus hoffmannseggi, which lives as a guest or commensal in the nests of ants.

 WOODPECKER, a bird that pecks or picks holes in wood, and from this habit is commonly reputed to have its name; but it is in some parts of England also known as “Woodspeight” (erroneously written “Woodspite”)—the latter syllable being cognate with Ger. Specht and Fr. Épeiche, possibly with Lat. Picus. More than 300 species have been described, and they have been very variously grouped by systematists; but all admit that they form a very natural family Picidae of Coraciiform

birds, their nearest allies being the toucans. They are generally of bright particoloured plumage, in which black, white, brown, olive, green, yellow, orange or scarlet—the last commonly visible on some part of the head—mingled in varying proportions, and most often strongly contrasted with one another, appear; while the less conspicuous markings take the form of bars, spangles, tear-drops, arrow-heads or scales. Woodpeckers inhabit most parts of the world, with the exception of Madagascar and the Australian Region, save Celebes and Flores; but it may be worth stating that no member of the group is known to have occurred in Egypt.

Of the three British species, the green woodpecker, Gecinus or Picus viridis, though almost unknown in Scotland or Ireland, IS the commonest, frequenting wooded districts, and more often heard than seen, its laughing cry (whence the name “Yaffil” or “Yaffle,” by which it is in many parts known), and undulating flight afford equally good means of recognition, even when it is not near enough for its colours to be discerned. About the size of a jay, its scarlet crown and bright yellow rump, added to its prevailing grass-green plumage, make it a sightly bird, and hence it often suffers at the hands of those who wish to keep its stuffed skin as an ornament. Besides the scarlet crown, the cock bird has a patch of the same colour running backward from the base of the lower mandible, a patch that in the hen is black. Woodpeckers in general are very shy birds, and to observe the habits of the species is not easy. Its ways, however, are well worth watching, since the ease with which it mounts, almost always spirally, the vertical trunks and oblique arms of trees as it searches the interstices of the bark fur its food, flying off when it reaches the smaller or upper branches—either to return to the base of the same tree and renew its course on a fresh fine, or to begin upon another tree near by—and the care it shows in its close examination, will repay a patient observer. The nest almost always consists of a hole chiselled by the bird's strong beak, impelled by very powerful muscles, in the upright trunk or arm of a tree, the opening being quite circular, and continued as a horizontal passage that reaches to the core, whence it is pierced downward for nearly a foot. There a chamber is hollowed out in which the eggs, often to the number of six, white, translucent and glossy, are laid with no bedding but a few chips that may have not been thrown out. The young are not only hatched entirely naked, but seem to become fledged without any of the downy growth common to most birds. Their first plumage is dull in colour, and much marked beneath with bars, crescents and arrowheads.

Of generally similar habits are the two other woodpeckers which inhabit Britain—the pied or greater spotted and the barred or lesser spotted woodpecker—Dendrocopus major and D. minor—each of great beauty, from the contrasted white, blue-black and scarlet that enter into its plumage. Both of these birds have an extraordinary habit of causing by quickly-repeated blows of their beak on a branch, or even on a small bough, a vibrating noise, louder than that of a watchman's rattle, and enough to excite the attention of the most incurious. Though the pied woodpecker is a resident in Britain, its numbers receive a considerable accession nearly every autumn. 