P I G P I G 85 of North America, Ectoputes migratorius, which is still plentiful in many parts of Canada and the United States, though no longer appearing in the countless numbers that it did of old, when a flock seen by Wilson was estimated to consist of more than 2230 millions. The often-quoted descriptions given by him and Audubon of Pigeon-haunts in the then " back woods " of Kentucky, Ohio, and Indiana need not here be reproduced. That of the latter was declared by Waterton to be a gross exaggeration if not an entire fabrication ; but the critic would certainly have changed his tone had he known that, some hundred and fifty years earlier, Passenger-Pigeons so swarmed and ravaged the colonists crops near Montreal that a bishop of his own church was constrained to exorcise them with holy water, as if they had been demons. 1 The rapid and sustained flight of these Pigeons is also as well-established as their former overwhelming abundance birds having been killed in the State of New York whose crops con tained undigested grains of rice that must have been not long before plucked and swallowed in South Carolina or Georgia. The Passenger-Pigeon is about the size of a common Turtle-Dove, but with a long, wedge-shaped tail. The male is of a dark slate-colour above, and purplish-bay beneath, the sides of the neck being enlivened by gleaming violet, green, and gold. The female is drab-coloured above and dull white beneath, with only a slight trace of the brilliant neck-markings. 2 Among the multitudinous forms of Pigeons very few can here be noticed. A species which seems worthy of attention as being one that might possibly repay the trouble of domestication, if any enterprising person would give it the chance, is the Wonga-wonga or White-fleshed Pigeon of Australia, Leucosarcia picata, a bird larger than the Ring-Dove, of a slaty-blue colour above and white beneath, streaked on the flanks with black. It is known to breed, though not very freely, in captivity, and is said to be excellent for the table. As regards flavour, however, those who have been so fortunate as to eat them declare that the Fruit-Pigeons of the genus Treron (or Vinago of some authors) and its allies surpass all birds. These inhabit tropical Africa, India, and especially the Malay Archipelago ; but the probability of domesticating any of them is very remote. Hardly less esteemed are the Pigeons of the genus Ptilopus and its kindred forms, which have their headquarters in the Pacific Islands, though some occur far to the westward, and also in Australia. Among them are found the most exquisitely-coloured of the whole Family. There may be mentioned the strange Nicobar Pigeon, Caloenas, an inhabitant of the Indian Archipelago, not less remarkable for the long Justrous hackles with which its neck is clothed than for the struc ture of its gizzard, which has been described by Prof. Flower (Proc. Zool. Society, 1860, p. 330), though this peculiarity is matched or even surpassed by that of the same organ in the PJtsenorrhina goliath of New Caledonia (Rev. de Zoologie, 1862, p. 138) and in the Carpophaga I/ (trans of Fiji. In this last the surface of the epithelial lining is beset by horny conical processes, adapted, it is believed, for crushing the very hard fruits of Onocarpus vitiensis on which the bird feeds (Proc. Zool. .Society, 1878, p. 102). The modern giants of the group, consisting of about half a dozen species of the genus Goura and known as 1 Voyages dn Baron de la Hontan dans V Amerique septentrionale, <<!. 2, Amsterdam, 1705, vol. i. pp. 93, 94. In the first edition, pub lished at The Hague in 1703, the passage, less explicit in details but to the same effect, is at p. 80. The author s letter, describing the cir cumstance, is dated May 1687. 2 There are several records of the occurrence in Britain of this Pigeon, but in most cases the birds noticed cannot be supposed to have found their own way hither. One, which was shot in Fife in 1825, may, however, have crossed the Atlantic unassisted by man. Crowned-Pigeons, belong to New Guinea and the neighbour ing islands, but want of space forbids further notice of their characteristics, of which the most conspicuous are their large size and the reticulated instead of scutellated cover ing of their " tarsi. " A very distinct type of Pigeon is that represented by Didunculus strigirostris, the " Manu-mea " of Samoa, still believed by some to be the next of kin to the DODO (vol. vii. p. 321), but really presenting only a superficial resemblance in the shape of its bill to that effete form, from which it differs osteologically quite as much as do other Pigeons (Phil. Transactions, 1869, p. 349). It re mains to be seen whether the Papuan genus Otidiphaps, of which several species are now known, may not belong rather to the Didunculidse than to the true Columbidx (see ORNITHOLOGY, vol. xviii. p. 46). At least 500 species of Pigeons have been described, and many methods of arranging them suggested. That by Garrod (Proc. Zool. Society, 1874, pp. 249-259) is one of the most recent ; but, for reasons before assigned (vol. xviii. p. 40), it is not satisfactory. Temminck s great work on the group with its continuation by M. Florent-Provost, already mentioned (vol. xviii. p. 11), is of course wholly out of date, as also Selby s more modest Natural History of the Columbidse, (forming vol. ix. of Jardine s Naturalist s Library). Schlegel s catalogue of the specimens contained in the museum at Leyden (Museum des Pays-Bas, livr. 10, 1873) contains much useful information, but a new monograph of the Pigeons, containing all the recent discoveries, is much wanted. (A. N.) PIGMENTS are coloured powders which, when mixed with oil, water, or other fluids, in which they are in soluble, form paints. They are distinguished from dyes and washes by their entire insolubility in the media in which they are mixed, whereas dye-stuffs are tinctorial sub stances applied in solution. Insoluble colours, when used in printing textile fabrics, are distinguished as pigment colours. The sources of materials available as pigments are numerous ; many are native coloured earths, others are separated from native metallic compounds and other mineral substances ; a large number are artificially pre pared from inorganic principally metallic sources; an important class consist of animal and vegetable colouring principles, forming with earthy bodies insoluble powders called lakes ; and the dye-stuffs artificially obtained from organic sources are also similarly utilized. In fact all substances coloured or neutral, capable of being presented in the form of impalpable powder, which at the same time are insoluble and unalterable under ordinary atmospheric influences, may be regarded as possible pigments. But there are many qualities practically essential in a pigment which limit the range of available substances. A con sideration of the first importance is the " body " or cover ing power of a pigment, that is, the property of fully covering and concealing with an opaque coating the surface over which it is spread. It is also important that the material should work well in, and be unaffected in appear ance and constitution by the medium with which it is made into a paint, and that it should spread in an even uniform coat, which should dry well and quickly in the air and adhere firmly to the surface to which it is applied. When dry it should possess durability and resist change under the action of weather and other influences to which paint is exposed. These are the principal qualities re quisite in paints in their important function of preserva tive coatings for the surfaces to which they are applied. On their artistic side, as decorative and pictorial materials, pigments should possess purity and brightness of colour with intensity of tinting power, capacity for mixing or
coming into contact with other colours without injuriously