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birds with silky plumage peculiar to the Amazon valley. They are often kept in houses, where they get very tame and affectionate; and they are useful in catching flies and other house insects, which they do with great perseverance and dexterity.
Islands of Tropical South America. These are few in number, and, with one exception, not of much interest. Such islands as Trinidad and Sta. Catherina form parts of South America, and have no peculiar groups of animals. The small islands of Fernando Noronha, Trinidad, and Martin Vaz, off the coast of Brazil, are the only Atlantic islands somewhat remote from land; while the Galapagos Archipelago in the Pacific is the only group whose productions have been carefully examined, or which present features of special interest.
Galapagos Islands.— These are situated on the equator, about 500 miles from the coast of Ecuador. They consist of the large Albemarle island, 70 miles long; four much smaller (18 to 25 miles long), named Narborough, James, Indefatigable, and Chatham Islands; four smaller still (9 to 12 miles long), named Abingdon, Bindloes, Hood's, and Charles Islands. All are volcanic, and consist of fields of black basaltic lava, with great numbers of extinct craters, a few which are still active. The islands vary in height from 1,700 to 5,000 feet, and they all rise sufficiently high to enter the region of moist currents of air, so that while the lower parts are parched and excessively sterile, above 800 or 1,000 feet there is a belt of comparatively green and fertile country.
These islands are known to support 58 species of Vertebrates, --1 quadruped, 52 birds and 5 reptiles, the greater part of which are found nowhere else, while a considerable number belong to peculiar and very remarkable genera.
remarkable genera. We must therefore notice them in ‘some detail.
Mammalia.—This class is represented by a mouse belonging to the American genus Hesperonys, but slightly different from any found on the continent. A true rat (Mus), slightly differing from any European species, also occurs; and as there can be little doubt that this is an escape from a ship, somewhat
changed under its new conditions of life (the genus Mus not being indigenous to the American continent), it is not improbable, as Mr. Darwin remarks, that the American mouse may also have been imported by man, and have become similarly changed.
Birds. Recent researches in the islands have increased the number of land-birds to thirty-two, and of wading and aquatic birds to twenty-three. All the land birds but two or three are peculiar to the islands, and eighteen, or considerably more than half, belong to peculiar genera. Of the waders 4 are peculiar, and of the swimmers 2. These are a rail (Porzana spilonota); two herons (Butorides plumbea and Nycticorax pauper); a flamingo (Phoenicopterus glyphorhynchus); while the new aquatics are a gull (Larus fuliginosus), and a penguin (Spheniscus mendiculus).
The land birds are much more interesting. All except the birds of prey belong to American genera which abound on the opposite coast or on that of Chili a little further south, or to peculiar genera allied to South American forms. The only species not peculiar are, Dolichonyx oryzivorus, a bird of very wide range in America and of migratory habits, which often visits the Bermudas 600 miles from North America, and Asio accipitrinus, an owl which is found almost all over the world. The only genera not exclusively American are Buteo and Strix, of each of which a peculiar species occurs in the Galapagos, although very closely allied to South American species. There remain 10 genera, all either American or peculiar to the Galapagos; and on these we will remark in systematic order.
1. Mimus, the group of American mocking-thrushes, is represented by three distinct and well-marked species. 2. Dendreca, an extensive and wide-spread genus of the wood-warblers (Mniotiltidæ), is represented by one species, which ranges over the greater part of the archipelago. The genus is especially abundant in Mexico, the Antilles, and the northern parts of
1 Mr. Salvin, who has critically examined the ornithological fauna of these islands, has kindly corrected my MS. List of the Birds, his valuable paper in the Transactions of the Zoological Society not having been published in time for me to make use of it.
tropical America, only one species extending south as far as Chili. 3. Certhidea, a peculiar genus originally classed among the finches, but which Mr. Sclater, who has made South American birds his special study, considers to belong to the Corebida, or sugar-birds, a family which is wholly tropical. Two species of this genus inhabit separate islands. 4. Progne, the American martins (Hirundinidæ), is represented by a peculiar species. 5. Geospiza, a peculiar genus of finches, of which no less than eight species occur in the archipelago, but not more than four in any one island. 6. Camarhynchus (6 sp.) and 7. Cactornis (4 sp.) are two other peculiar genera of finches; some of the species of which are confined to single islands, while others inhabit several. 8. Pyrocephalus, a genus of the American family of tyrant-flycatchers (Tyrannidæ), has one peculiar species closely allied to T. rubineus, which has a wide range in South America. 9. Myiarchus, another genus of the same family which does not range further south than western Ecuador, has also a representative species found in several of the islands. 10. Zenaida, an American genus of pigeons, has a species in James Island and probably in some of the others, closely allied to a species from the west coast of America.
It has been already stated that some of the islands possess peculiar species of birds distinct from the allied forms in other islands, but unfortunately our knowledge of the different islands is so unequal and of some so imperfect, that we can form no useful generalizations as to the distribution of birds among the islands themselves. The largest island is the least known; only one bird being recorded from it, one of the mocking-thrushes found nowhere else. Combining the observations of Mr. Darwin with those of Dr. Habel and Prof. Sundevall, we have species recorded as occurring in seven of the islands. Albemarle island has but one definitely known species ; Chatham and Bindloe islands have 11 each ; Abingdon and Charles islands 12 each; Indefatigable island and James island have each 18 species. This shows that birds are very fairly distributed over all the islands, one of the smallest and most remote (Abingdon) furnishing as many as the much larger Chatham Island, which is also the nearest to the mainland. Taking the six islands which seem tolerably explored, we find that two of the species (Dendroca aureola and Geospizo fortis) occur in all of them; two others (Geospiza strenua and Myiarchus magnirostris) in five; four (Mimus melanotis, Geospiza fuliginosa, G. parvula, and Camarhynchus prosthemelas) in four islands; five (Certhidea olivacea, Cactornis scandens, Pyrocephalus nanus), and two of the birds of prey, in three islands; nine (Certhidea fusca, Progne concolor, Geospiza nebulosa, G. magnirostris, Camarhynchus psittaculus, C. variegatus, C. habeli and Asio accipitrinus) in two islands; while the remaining ten species are confined to one island each. These peculiar species are distributed among the islands as follows. James, Charles and Abingdon islands, have 2 each ; Bindloes, Chatham, and Indefatigable, 1 each. The amount of speciality of James Island is perhaps only apparent, owing to our ignorance of the fauna of the adjacent large Albemarle island; the most remote islands north and south, Abingdon and Charles, have no doubt in reality most peculiar species, as they appear to have. The scarcity of peculiar species in Chatham Island is remarkable, it being large, very isolated, and the nearest to the mainland. There is still room for exploration in these islands, especially in Albemarle, Narborough, and Hood's islands of which we know nothing.
Reptiles.--The few reptiles found in these islands are very interesting. There are two snakes, a species of the American genus Herpetodryas, and another which was at first thought to be a Chilian species (Psammophis Temminckii), but which is now considered to be distinct. Of lizards there are four at least, belonging to as many genera. One is a species of Phyllodactylus, a wide-spread genus of Geckotidæ; the rest belong to the American family of the Iguanas, one being a species of the Neotropical genus Leiocephalus, the other two very remarkable forms, Trachycephalus and Oreocephalus (formerly united in the genus Amblyrhynchus). The first is a land, the second a marine, lizard; both are of large size and very abundant on all the islands; and they are quite distinct from any of the very numerous genera of Iguanidæ, spread all over the American continent. The last
reptile is a land tortoise (Testudo nigra) of immense size, and also abundant in all the islands. Its nearest ally is the equally large species of the Mascarene Islands; an unusual development due, in both cases, to the absence of enemies permitting these slow but continually growing animals to attain an immense age. It is believed that each island has a distinct variety or species of tortoise.
Insects.-Almost the only insects known from these islands are some Coleoptera, chiefly collected by Mr. Darwin. They consist of a few peculiar species of American or wide ranging genera, the most important being, a Calosoma, Pæcilus, Solenophorus, and Notaphus, among the Carabidæ ; an Oryctes among the Lamellicornes; two new genera of obscure Heteromera; two Curculionidæ of wide-spread genera; a Longicorn of the South American genus Eburia; and two small Phytophaga, -a set of species highly suggestive of accidental immigrations at rare and distant intervals.
Land-Shells. These consist of small and obscure species, forming two peculiar sub-genera of Bulimulus, a genus greatly developed on the whole West coast of America ; and a single species of Buliminus, a genus which ranges over all the world except America. As in the case of the birds, most of the islands have two or three peculiar species.
General Conclusions. These islands are wholly volcanic and surrounded by very deep sea; and Mr. Darwin is of opinion, not only that the islands have never been more nearly connected with the mainland than at present, but that they have never been connected among themselves. They are situated on the Equator, in a sea where gales and storms are almost unknown. The main currents are from the south-west, an extension of the Peruvian drift along the west coast of South America. From their great extent, and their volcanoes being now almost extinct, we may assume that they are of considerable antiquity. These facts exactly harmonize with the theory, that they have been peopled by rare accidental immigrations at very remote intervals. The only peculiar genera consist of birds and lizards, which must therefore have been the earliest