Zealand, Tristan d'Acunha, and other oceanic islands; and the phenomenon is clearly dependent on the long-continued absence of enemies, which allowed of great increase of bulk and the total loss of the power of flight, without injury. In some few cases (the Ostrich for example) birds incapable of flight co-exist with large carnivorous mammalia; but these birds are large and powerful, as well as very swift, and are thus able to escape from some enemies and defend themselves against others. The entire absence of the smaller and more defenceless ground-birds from the adjacent island of Madagascar, is quite in accordance with this view, because that island has several small but destructive carnivorous animals.

General Remarks on the Distribution of the Columbæ.

The striking preponderance of Pigeons, both as to genera and species, in the Australian region, would seem to indicate that at some former period it possessed a more extensive land area in which this form of bird-life took its rise. But there are other considerations which throw doubt upon this view. The western half of the Malay Archipelago, belonging to the Oriental region, is also rich in pigeons, since it has 43 species belonging to 11 genera, rather more than are found in all the rest of the Oriental region. Again, we find that the Mascarene Islands and the Antilles both possess more pigeons than we should expect, in proportion to those of the regions to which they belong, and to their total amount of bird-life. This looks as if islands were more favourable to pigeon-development than continents; and if we group together the Pacific and the Malayan Islands, the Mascarene group and the Antilles, we find that they contain together about 170 species of pigeons belonging to 24 out of the 47 genera here adopted; while all the great continents united only produce about the same number of species belonging (if we omit those peculiar to Australia) to only 20 genera. The great development of the group in the Australian region may, therefore, be due to its consisting mainly of islands, and not to the order having originated there, and thus having had a longer period in which to develop. I have elsewhere suggested (Ibis 1865, p. 366)

a physical cause for this peculiarity of distribution. Pigeons build rude, open nests, and their young remain helpless for a considerable period. They are thus exposed to the attacks of such arboreal quadrupeds or other animals as feed on eggs or young birds. Monkeys are very destructive in this respect; and it is a noteworthy fact that over the whole Australian region, the Mascarene Islands and the Antilles, monkeys are unknown. In the Indo-Malay sub-region, where monkeys are generally plentiful, the greatest variety of pigeons occurs in the Philippines, where there is but a single species in one island; and in Java, where monkeys are far less numerous than in Sumatra or Borneo. If we add to this consideration the fact, that mammalia and rapacious birds are, as a rule, far less abundant in islands than on continents; and that the extreme development of pigeon-life is reached in the Papuan group of islands, in which mammalia (except a few marsupials, bats, and pigs) are wholly absent, we see further reason to adopt this view. It is also to be noted that in America, comparatively few pigeons are found in the rich forests (comparable to those of the Australian insular region in which they abound), but are mostly confined to the open campos, the high Andes, and the western coast districts, from which the monkey-tribe are wholly absent.

This view is further supported by the great development of colour that is found in the pigeons of these insular regions, culminating in the golden-yellow fruit-dove of the Fiji Islands, the metallic green Nicobar-pigeon of Malaya, and the black and crimson Alectronas of Mauritius. Here also, alone, we meet with crested pigeons, rendering the possessors more conspicuous; such as the Lopholaimus of Australia and the crowned Goura of New Guinea; and here too are more peculiar forms of terrestrial pigeons than elsewhere, though none have completely lost the power of flight but the now extinct Dididæ.

The curious liking of pigeons for an insular habitat is well shown in the genera Ianthanas and Calonas. The former, containing 11 species, ranges over a hundred degrees of longitude, and forty-five of latitude, extending into three regions, yet nowhere inhabits a continent or even large island. It is

found in the Andaman and Nicobar Islands; in the Philippines, Gilolo, and the smaller Papuan Islands, and in Japan; yet not in any of the large Malay Islands or in Australia. The other genus, Calanas, consists of but a single species, yet this ranges from the Nicobar Islands to New Guinea. It is not, however, as far as known, found on any of the large islands, but seems to prefer the smaller islands which surround them. We here have the general preference of pigeons for islands, further developed in these two genera into a preference for small islands; and it is probable that the same cause—the greater freedom from danger— has produced both phenomena.

Of the geological antiquity of the Columbæ we have no evidence; but their wide distribution, their varied forms, and their great isolation, all point to an origin, at least as far back as that we have assigned as probable in the case of the Parrots.

Order V-GALLINE.

FAMILY 86. PTEROCLIDE. (2 Genera, 16 Species.)

The Pteroclidæ, or Sand-grouse, are elegantly formed birds with pointed tails, and plumage of beautifully varied protective tints, characteristic of the Ethiopian region and Central Asia, though extending into Southern Europe and Hindostan. Being preeminently desert-birds, they avoid the forest-districts of all these countries, but abound in the most arid situations and on the most open and barren plains. The distribution of the genera is as follows:

:

8

Pterocles (14 sp.), has the same range as the family; Syrrhaptes (2 sp.), normally inhabits Tartary, Thibet, and Mongolia to the country around Pekin, and occasionally visits Eastern Europe. But a few years back (1863) great numbers suddenly appeared in

Europe and extended westward to the shores of the Atlantic, while some even reached Ireland and the Færoes. (Plate III. Vol. I. p. 226.)

FAMILY 87.-TETRAONIDE. (29 Genera, 170 Species.)

The Tetraonidæ, including the Grouse, Partridges, Quails, and allied forms, abound in all parts of the Eastern continents; they are less plentiful in North America and comparatively scarce in South America, more than half the Neotropical species being found north of Panama; and in the Australian region there are only a few of small size. The Ethiopian region probably contains most species; next comes the Oriental-India proper from the Himalayas to Ceylon having twenty; while the Australian region, with 15 species, is the poorest. These facts render it probable that the Tetraonidæ are essentially denizens of the great northern continents, and that their entrance into South America, Australia, and even South Africa, is, comparatively speaking, recent. They have developed into forms equally suited to the tropical plains and the arctic regions, some of them being among the few denizens of the extreme north, as well as of the highest alpine snows. The genera are somewhat unsettled, and there is even some uncertainty as to the limits between this family and the next; but the following are those now generally admitted:

Ptilopachus (1 sp.), West Africa; Francolinus (34 sp.), all Africa, South Europe, India to Ceylon, and South China; Ortygornis (3 sp.), Himalayas to Ceylon, Sumatra, and Borneo: Peliperdix (1 sp.), West Africa; Perdix (3 sp.), the whole Continental Palæarctic region; Margaroperdix (1 sp.), Madagascar; Oreoperdix (1 sp.), Formosa; Arborophila (8 sp.), the Oriental Continent and the Philippines; Peloperdix (4 sp.), Tenasserim and Malaya; Coturnix (21 sp.), Temperate Palæarctic, Ethiopian and

Oriental regions, and the Australian to New Zealand; Rollulus (2 sp.), Siam to Sumatra, Borneo, and Philippines; Caloperdix (1 sp.), Malacca and Sumatra; Odontophorus (17 sp.), Brazil and Peru to Mexico; Dendrortyx (3 sp.), Guatemala and Mexico; Cyrtonyx (3 sp.), Guatemala to New Mexico; Ortyx (8 sp.), Honduras and Cuba to Canada; Eupsychortyx (6 sp.), Brazil and Ecuador to Mexico; Callipepla (3 sp.), Mexico to California; Lophortyx (2 sp.), Arizona and California; Oreortyx (1 sp.), California and Oregon (Plate XVIII., Vol. II. p. 128); Lerwa (1 sp.), Snowy Himalayas and East Thibet; Caccabis (10 sp.), Palæarctic region to Abyssinia, Arabia and the Punjaub; Tetraogallus (4 sp.), Caucasus and Himalayas to Altai Mountains; Tetrao (7 sp.), northern parts of Palearctic and Nearctic regions; Centrocercus (1 sp.), Rocky Mountains; Pediocætes (2 sp.), North and North-west America (Plate XVIII. Vol. II. p. 128); Cupidonia (1 sp.), East and North-Central United States and Canada; Bonasa (3 sp.), north of Nearctic and Palearctic regions; Lagopus (6 sp.), Arctic Zone and northern parts of Nearctic and Palearctic regions.

FAMILY 88.-PHASIANIDE. (18 Genera, 75 Species.)

The Phasianidæ, including the Pea-fowl, Pheasants, and Junglefowl, the Turkeys, and the Guinea-fowl, are very widely distributed, but are far more abundant than elsewhere in the Eastern parts of Asia, both tropical and temperate. Leaving out the African guinea-fowls and the American turkeys, we have 13 genera and 63 species belonging to the Oriental and Palearctic regions. These are grouped by Mr. Elliot (whose arrangement we mainly follow) in 5 sub-families, of which 3-Pavonniæ, Euplocaminæ, and Gallinæ—are chiefly Oriental, while the Lophophorniæ and Phasianinæ are mostly Palearctic or from the highlands on the