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This family contains a single bird—the Guacharo–forming the genus Steatornis, first discovered by Humboldt in a cavern in Venezuela, and since found in deep ravines near Bogota, and also in Trinidad. Although apparently allied to the Goat-suckers it is a vegetable-feeder, and is altogether a very anomalous bird whose position in the system is still undetermined.

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The Goat-suckers, or Night-jars, are crepuscular insectivorous birds, which take their prey on the wing, and are remarkable for their soft and beautifully mottled plumage, swift and silent flight, and strange cries often imitating the human voice. They are universally distributed, except that they do not reach New Zealand or the remoter Pacific Islands. The South American genus, Nyctibius, differs in structure and habits from the other goat-suckers and should perhaps form a distinct family. More than half the generainhabit the Neotropical region. The genera are as follows:– Nyctibius (6 sp.), Brazil to Guatemala, Jamaica; Caprimulgus (35 sp.), Palaearctic, Oriental, and Ethiopian regions, with the Austro-Malay Islands and North Australia; Hydropsalis (8 sp.), Tropical South America to La Plata ; Antrostomus (10 sp.), La Plata and Bolivia to Canada, Cuba; Stenopsis (4 sp.), Martinique to Columbia, West Peru and Chili; Siphonorhis (1 sp.), Jamaica; Heleothreptus (1 sp.), Demerara: Nyctidromus (2 sp.), South Brazil to Central America; Scortornis (3 sp.), West and East Africa; Macrodipterya: (2 sp.), West and Central Africa; Cosmetornis (1 sp.), all Tropical Africa; Podager (1 sp.), Tropical South America to La Plata; Lurocalis (2 sp.), Brazil and Guiana; Chordeiles (8 sp.), Brazil and West Peru to Canada, Porto Rico, Jamaica; Nyctiprogne (1 sp.), Brazil and Amazonia ; Eurostopodus (2 sp.), Australia and Papuan Islands; Lyncornis (4 sp.), Burmah, Philippines, Borneo, Celebes.

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The Swifts can almost claim to be a cosmopolitan group, but for their absence from New Zealand. They are most abundant both in genera and species in the Neotropical and Oriental regions. The following is the distribution of the genera:

Cypselus (1 sp.), absent only from the whole of North America and the Pacific; Panyptila (3 sp.), Guatemala and Guiana, and extending into North-west America; Collocalia (10 sp.), Madagascar, the whole Oriental region and eastward through New Guinea to the Marquesas Islands; Dendrochelidon (5 sp.), Oriental region and eastward to New Guinea; Chaptura (15 sp.), Continental America (excluding South Temperate), West Africa and Madagascar, the Oriental region, North China and the Amoor, Celebes, Australia; Hemiprocne (3 sp.), Mexico to La Plata, Jamaica and Hayti; Cypseloides (2 sp.), Brazil and Peru; Nephaecetes (2 sp.), Cuba, Jamaica, North-west America.

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The wonderfully varied and beautiful Humming-Birds are confined to the American continent, where they range from Sitka-to Cape Horn, while the island of Juan Fernandez has two peculiar species. Only 6 species, belonging to 3 genera, are found in the Nearctic region, and most of these have extended their range from the south. They are excessively abundant in the forest-clad Andes from Mexico to Chili, some species extending up to the limits of perpetual snow; but they diminish in number and variety in the plains, however luxuriant the vegetation. In place of giving here the names and distribution of the numerous genera into which they are now divided (which will be found in the tables of the genera of the Neotropical region), it may be more useful to present a summary of their distribution in the sub-divisions of the American continent, as follows:—

Sub- Sub- Sub. Sub- Nearctic region I. region II. region III. region IV, region. (Pafagonia (Tropical (Tropical (Antilles.) (Temp.

& S. Andes.) S. Amer.) (N. Amer.) N. Amer.)

Genera in each Sub-region 10 90 41 - 8 3
Peculiar Genera ... ... 3 58 14 5 0
Species in each Sub-region 15 275 100 15 6

The island of Juan Fernandez has two species, and Masafuera, an island beyond it, one; the three forming a peculiar genus. The island of Tres Marias, about 60 miles from the west coast of Mexico, possesses a peculiar species of humming-bird, and the Bahamas two species; but none inhabit either the Falkland Islands or the Galapagos.

Like most groups which are very rich in species and in generic forms, the humming-birds are generally very local, small generic groups being confined to limited districts; while single mountains, valleys, or small islands, often possess species found nowhere else. It is now well ascertained that the Trochilidae are really insectivorous birds, although they also feed largely, but probably never exclusively, on the nectar of flowers. Their nearest allies are undoubtedly the Swifts; but the wide gap that now separates them from these, as well as the wonderful variety of form and of development of plumage, that is found among them, alike point to their origin, at a very remote period, in the forests of the once insular Andes. There is perhaps no more striking contrast of the like nature, to be found, than that between the American kingfishers—confined to a few closely allied forms of one Old World genus—and the American humming-birds with more than a hundred diversified generic forms unlike everything else upon the globe; and we can hardly imagine any other cause for this difference, than a (comparatively) very recent introduction in the one case, and a very high antiquity in the other.

General Remarks on the Distribution of the Picariae.

The very heterogeneous mass of birds forming the Order Picariae, contains 25 families, 307 genera and 1,604 species. This gives about 64 species to each family, while in the Passeres the proportion is nearly double, or 111 species per family. There are, in fact, only two very large families in the Order, which happen to be the first and last in the series—Picidae and Trochilidae. Two others—Cuculidae and Alcedinidae—are rather large; while the rest are all small, seven of them consisting only of a single genus and from one to a dozen species. Only one of the families—Alcedinidae—is absolutely cosmopolitan, but three others are nearly so, Caprimulgidae and Cypselidae being only absent from New Zealand, and Cuculidae from the Canadian Sub-region of North America. Eleven families inhabit the Old World only, while seven are confined to the New World, only one of these—Trochilidae —being common to the Neotropical and Nearctic regions. The Picariae are highly characteristic of tropical faunas, for while no less than 15 out of the 25 families are exclusively tropical, none are confined to, or have their chief development in, the temperate regions. They are best represented in the Ethiopian region, which possesses 17 families, 4 of which are peculiar to it; while the Oriental region has only 14 families, none of which are peculiar. The Neotropical region has also 14 families, but 6 of them are peculiar. The Australian region has 8, the Palaearctic 9 and the Nearctic 6 families, but none of these are peculiar. We may see a reason for the great specialization of this tropical assemblage of birds in the Ethiopian and Neotropical regions, in the fact of the large extent of land on both sides of the Equator which these two regions alone possess, and their extreme isolation either by sea or deserts from other regions,—an isolation which we know was in both cases much greater in early Tertiary times. It is, perhaps, for a similar reason that we here find hardly any trace of the connection between Australia and South America which other groups exhibit; for that connection has most probably been effected by a former communication between the temperate southern extremities of those two continents. The most interesting and suggestive fact, is that presented by the distribution of the Megalaemidae and Trogonidae over the tropics of America, Africa, and Asia. In the absence of palaeontological evidence as to the former history of the Megalaemidae, we are unable to say positively, whether it owes its present distribution to a former closer union between these continents in intertropical latitudes, or to a much greater northern range of the group at the period when a luxuriant sub-tropical vegetation extended far toward the Arctic regions; but the discovery of Trogon in the Miocene deposits of the South of France renders it almost certain that the latter is the true explanation in the case of both these families. The Neotropical region, owing to its enormous family of humming-birds, is by far the richest in Picariae, possessing nearly half the total number of species, and a still larger proportion of genera. Three families, the Bucerotidae, Meropidae and Coraciidae are equally characteristic of the Oriental and

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