Fresh-water fishes.—The great rivers of Tropical America abound in fish of many strange forms and peculiar types. Three families, and three sub-family groups are peculiar, while the number of peculiar genera is about 120. The peculiar families are Polycentridæ, with two genera; Gymnotidæ, a family which includes the electric eels, (5 genera); and Trygonidæ, the rays, which are everywhere marine except in the great rivers of South America, where many species are found, belonging to two genera. Of the extensive family Siluridæ, three sub-families Siluridæ anomalopteræ, S. olisthopteræ, and S. branchiolæ, are confined to this region. The larger and more important of the peculiar genera are the following:Percilia, inhabiting Chilian andPercichthysSouth Temperate rivers, belong to the Perch family (Percidæ);Acharnes, found only in Guiana, belongs to the Nandidæ, a family of wide range in the tropics; the Chromidæ, a family of exclusively fresh-water fishes found in the tropics of the Ethiopian, Oriental and Neotropical regions, are here represented by 15 genera, the more important beingAcara(17 sp.),Heros(26 sp.),Crenicichla(9 sp.),Satanoperca(7 sp.). Many of these fishes are beautifully marked and coloured. The Siluridæ proteropteræ are represented by 14 genera, of whichPimelodus(42 sp.), andPlatystoma(11 sp.), are the most important; the Siluridæ stenobranchiæ by 11 genera, the chief beingDoras(13 sp.),Auchenipterus(9 sp.), andOxydoras(7 sp.). The Siluridæ proteropodes are represented by 16 genera, many of them being among the most singular of fresh-water fishes, clothed in coats of mail, and armed with hooks and serrated spines. The following are the most important,—Chætostomus(25 sp.),Loricaria(17 sp.),Plecostonus(15 sp.) andCallichthys(11 sp.). The Characinidæ are divided between Tropical America and Tropical Africa, the former possessing about 40 genera and 200 species. The Haplochitonidæ are confined to South America and Australia; the American genus beingHaplochiton. The Cyprinodontidæ are represented by 18 genera, the most important being,Pæcilia(16 sp.),Girardinus(10 sp.), andGambusia(8 sp.) The Osteoglossidæ, found in Australian and African rivers, are represented in South America by the peculiarArapaima, the "pirarucu" of theAmazon. The ancient Sirenoidei, also found in Australia and Africa, have theLepidosirenas their American representative. Lastly,Ellipisurusis a genus of rays peculiar to the fresh waters of South America. We may expect these numbers to be largely increased and many new genera to be added, when the extensive collections made by Agassiz in Brazil are described.
Summary of Neotropical Vertebrates.—Summarizing the preceding facts, we find that the Neotropical region possesses no less than 45 families and more than 900 genera of Vertebrata which are altogether peculiar to it; while it has representatives of 168 families out of a total of 330, showing that 162 families are altogether absent. It has also representatives of 131 genera of Mammalia of which 103 are peculiar to it, a proportion of4⁄5; while of 683 genera of land-birds no less than 576 are peculiar, being almost exactly5⁄6of the whole. These numbers and proportions are far higher than in the case of any other region.
Insects.
The Neotropical region is so excessively rich in insect life, it so abounds in peculiar groups, in forms of exquisite beauty, and in an endless profusion of species, that no adequate idea of this branch of its fauna can be conveyed by the mere enumeration of peculiar and characteristic groups, to which we are here compelled to limit ourselves. Our facts and figures will, however, furnish data for comparison; and will thus enable those who have some knowledge of the entomology of any other country, to form a better notion of the vast wealth of insect life in this region, than a more general and picturesque description could afford them.
Lepidoptera.—The Butterflies of South America surpass those of all other regions in numbers, variety and beauty; and we find here, not only more peculiar genera and families than elsewhere, but, what is very remarkable, a fuller representation of the whole series of families. Out of the 16 families of butterflies in all parts of the world, 13 are found here, and 3 of these are wholly peculiar—Brassolidæ, Heliconidæ, and Eurygonidæ, with a fourth, Erycinidæ, which only extends into the Nearcticregion; so that there are 4 families peculiar to America. These four families comprise 68 genera and more than 800 species; alone constituting a very important feature in the entomology of the region. But in almost all the other families there are numbers of peculiar genera, amounting in all to about 200, or not far short of half the total number of genera in the world—(431). We must briefly notice some of the peculiarities of the several families, as represented in this region. The Danaidæ consist of 15 genera, all peculiar, and differing widely from the generally sombre-tinted forms of the rest of the world. The delicate transparent-winged Ithomias of which 160 species are described, are the most remarkable.Melinæa,Napeogenes,CeratinaandDircennaare more gaily coloured, and are among the chief ornaments of the forests. The Satyridæ are represented by 25 peculiar genera, many of great beauty; the most remarkable and elegant being the genusHæteraand its allies, whose transparent wings are delicately marked with patches of orange, pink, or violet. The genusMorphois perhaps the grandest development of the butterfly type, being of immense size and adorned with the most brilliant azure tints, which in some species attain a splendour of metallic lustre unsurpassed in nature. The Brassolidæ are even larger, but are crepuscular insects, with rich though sober colouring. The true Heliconii are magnificent insects, most elegantly marked with brilliant and strongly contrasted tints. The Nymphalidæ are represented by such a variety of gorgeous insects that it is difficult to select examples. Prominent are the generaCatagrammaandCallithea, whose exquisite colours and symmetrical markings are unique and indescribable; and these are in some cases rivalled byAgriasandPrepona, which reproduce their style of coloration although not closely allied to them. The Erycinidæ, consisting of 59 genera and 560 species, comprise the most varied and beautiful of small butterflies; and it would be useless to attempt to indicate the unimaginable combinations of form and colour they present. It must be sufficient to say that nothing elsewhere on the globe at all resembles them. In Lycænidæ the world-wide genusTheclais wonderfully developed, and the SouthAmerican species not only surpass all others in size and beauty, but some of them are so gorgeous on the under surface of their wings, as to exceed almost all the combinations of metallic tints we meet with in nature. The last family, Hesperidæ, is also wonderfully developed here, the species being excessively numerous, while some of them redeem the character of this generally sober family, by their rich and elegant coloration.
In the only other group of Lepidoptera we can here notice, the Sphingina, the Neotropical region possesses some peculiar forms. The magnificent diurnal butterfly-like moths,Urania, are the most remarkable; and they are rendered more interesting by the occurrence of a species closely resembling them in Madagascar. Another family of day-flying moths, the Castniidæ, is almost equally divided between the Neotropical and Australian regions, although the genera are more numerous in the latter. The American Castnias are large, thick-bodied insects, with a coarse scaly surface and rich dull colours; differing widely from the glossy and gaily coloured Agaristas, which are typical of the family in the East.
Coleoptera.—This is so vast a subject that, as in the case of the regions already treated, we must confine our attention to a few of the more important and best known families as representatives of the entire order.
Cicindelidæ.—We find here examples of 15 out of the 35 genera of these insects; and 10 of these genera are peculiar. The most important areOxychila(11 sp.),Hiresia(14 sp.), andCtenostoma(26 sp.).Odontochila(57 sp.) is the most abundant and characteristic of all, but is not wholly peculiar, there being a species in the Malay archipelago.Tetracha, another large genus, has species in Australia and a few in North America and Europe. The small genusPeridexiais divided between Brazil and Madagascar,—a somewhat similar distribution to that ofUranianoticed above. One genus,Agrius, is confined to the southern extremity of the continent.
Carabidæ.—Besides a considerable number of cosmopolitan or wide-spread genera, this family is represented by more than 100 genera which are peculiar to the Neotropical region. Themost important of these areAgra(150 sp.),Ardistonus(44 sp.),Schizogenius(25 sp.),Pelecium(24 sp.),Calophena(22 sp.),Aspidoglossa(21 sp.), andLia,Camptodonotus,Stenocrepis, andLachnophorus, with each more than 12 species. These are all tropical; but there are also a number of genera (26) peculiar to Chili and South Temperate America. The most important of these areAntarctia(29 sp,), all except two or three confined to South Temperate America;Scelodontis(10 sp.), mostly Chilian;Feronomorpha(6 sp.) all Chilian; andTropidopterus(4 sp.), all Chilian.Helluomorpha(18 sp.), is confined to North and South America;Galerita,Callida, andTetragonoderus, are large genera which are chiefly South American but with a few species scattered over the other tropical regions,CasnoniaandLebiaare cosmopolite, but most abundant in South America.Pachytelesis mostly South American but with a few species in West Africa; whileLobodonotushas one species in South America and two in Africa.
Lucanidæ.—The Neotropical species of this family almost all belong to peculiar genera. Those common to other regions areSyndesus, confined to Tropical South America and Australia, andPlatyceruswhich is Palæarctic and Nearctic, with one species in Brazil. The most remarkable genus is undoubtedlyChiasognathus, confined to Chili. These are large insects of metallic green colours, and armed with enormous serrated mandibles. The allied genera,PholidotusandSphenognathus, inhabit Tropical South America.Streptocerusconfined to Chili, is interesting, as being allied to the AustralianLamprima. The other genera present no remarkable features; butSclerognathusandLeptinopteraare the most extensive.
Cetoniidæ.—These magnificent insects are but poorly represented in America; the species being mostly of sombre colours. There are 14 genera, 12 of which are peculiar. The most extensive genus isGymnetis, which, with its alliesCotinisandAllorhina, form a group which comprehends two-thirds of the Neotropical species of the family. The only other genera of importance are,Inca(7 sp.), remarkable for their large size, and being the only American group in which horns are developed on the head;andTrigonopeltastes(6 sp.), allied to the EuropeanTrichius. The non-peculiar genera are,Stethodesma, of which half the species are African and half tropical American; andEuphoria, confined to America both North and South.
Buprestidæ.—In this fine group the Neotropical region is tolerably rich, having examples of 39 genera, 18 of which are peculiar to it. Of these, the most extensive areConognathaandHalecia, which have a wide range over most parts of the region; andDactylozodes, confined to the south temperate zone. Of important genera which range beyond the region,Dicercais mainly Nearctic and Palæarctic;Cinyrahas a species in North America and one in Australia;Curisis divided between Chili and Australia; the Australian genusStigmoderahas a species in Chili;Polycestahas a species in Madagascar, two in the Mediterranean region, and a few in North America;Acherusiais divided between Australia and Brazil;Ptosimahas one species in south temperate America, the rest widely scattered from North America to the Philippines;Actenodeshas a single species in North America and another in West Africa;Colobogasterhas two in West Africa, one in Java and one in the Moluccas. The relations of South America and Australia as indicated by these insects has already been sufficiently noticed under the latter region.
Longicornia.—The Neotropical Longicorn Coleoptera are overwhelming in their numbers and variety, their singularity and their beauty. In the recent Catalogue of Gemminger and Harold, it is credited with 516 genera, 489 of which are peculiar to it; while it has only 5 genera in common (exclusively) with the Nearctic, and 4 (in the same way) with the Australian region. Only the more important genera can be here referred to, under the three great families into which these insects are divided.
The Prionidæ are excessively numerous, being grouped in 64 genera, more than double the number possessed by any other region; and 61 of these are peculiar. The three, common to other regions, are,ParandraandMallodon, which are widely distributed; andErgates, found also in California and Europe. The most remarkable genera are, the magnificently-colouredPsalidognathusandPyrodes; the large and strangely markedMacrodontia; andTitanus, the largest insect of the entire family.
Of the Cerambycidæ there are 233 genera, exceeding by one-half, the number in any other region; and 225 of these are peculiar. Only 2 are common to the Neotropical and Nearctic regions exclusively, and 3 to the Neotropical and Australian. The most extensive genera are the elegantIbidion(80 sp.); the richly-colouredChrysoprasis(47 sp.); the prettily-markedTrachyderes(53 sp.); withOdontocera(25 sp.);Criodon(22 sp.); and a host of others of less extent, but often of surpassing interest and beauty. The noteworthy genera of wide range are,OemeandCyrtomerus, which have each a species in West Africa, andHammatocerus, which has one in Australia.
The Lamiidæ have 219 genera, and this is the only tropical region in which they do not exceed the Cerambycidæ. This number is almost exactly the same as that of the Oriental genera, but here there are more peculiar groups, 203 against 160 in the other region. The most extensive genera areHemilophus(80 sp.),Colobothea(70 sp.),Acanthoderes(56 sp.),Oncoderes(48 sp.),Lepturgus(40 sp.),Hypsioma(32 sp.), andTæniotes(20 sp.).Macropus longimanus, commonly called the harlequin beetle, is one of the largest and most singularly-marked insects in the whole family.Leptostylushas a single species in New Zealand;Acanthodereshas one species in Europe, W. Africa, and Australia, respectively;Spalacopsishas a species in W. Africa;Pachypezais common to S. America and the Philippines;Mesosais Oriental and Palæarctic, but has one species on the Amazon;Apomecynaranges through the tropics of the Eastern Hemisphere, but has two species in S. America;Acanthocinushas one species in Tasmania, and the rest in South America, North America, and Europe;Phæais wholly Neotropical, except two species in the Philippine Islands.
General Conclusions as to the Neotropical Insect-fauna.—Looking at the insects of the Neotropical region as a whole, we are struck with the vast amount of specialty they present; and, considering how many causes there are which must lead to the dispersal of insects, the number of its groups which are scatteredover the globe is not nearly so great as we might expect. This points to a long period of isolation, during which the various forms of life have acted and reacted on each other, leading to such a complex yet harmoniously-balanced result as to defy the competition of the chance immigrants that from time to time must have arrived. This is quite in accordance with the very high antiquity we have shown most insect-forms to possess; and it is no doubt owing to this antiquity, that such a complete diversity ofgenericforms has been here brought about, without any important deviation from the greatfamilytypes which prevail over the rest of the globe.
Land Shells.—The Neotropical region is probably the richest on the globe in Terrestrial Mollusca, but this is owing, not to any extreme productiveness of the equatorial parts of the continent, where almost all other forms of life are so largely developed, but to the altogether exceptional riches of the West India Islands. The most recent estimates show that the Antilles contain more species of land shells than all the rest of the region, and almost exactly as many as all continental America, north and south.
Mr. Thomas Bland, who has long studied American land shells, points out a remarkable difference in the distribution of the Operculated and Inoperculated groups, the former being predominant on the islands, the latter on the continent. The Antilles possess over 600 species of Operculata, to about 150 on the whole American continent, the genera being as 22 to 14. Of Inoperculata the Antilles have 740, the Continent 1,250, the genera being 18 and 22. The proportions of the two groups in each country are, therefore:
The extensive family of the Helicidæ is represented by 22 genera, of which 6 are peculiar.Spiraxisis confined to Central America and the Antilles;StenopusandSagdaare Antillean only;Orthalicus,Macroceramus, andBulimulushave a wider range, the last two extending into the southern UnitedStates. Important and characteristic genera are,Glandina, in all the tropical parts of the region;Cylindrella, in Central America and the Antilles;Bulimus, containing many large and handsome species in South America;Stenogyra, widely spread in the tropics; andStreptaxis, in Tropical South America.
Among the Operculata, the Aciculidæ are mostly Antillean, two genera being peculiar there, and one,Truncatella, of wide distribution, but most abundant in the West Indian Islands. The Cyclostomidæ are represented by 15 genera, 9 being peculiar to the region, and 5 of these (belonging to the sub-family Licinidæ) to the Antilles only. Of these peculiar generaCistulaandChondropomaare the most important, ranging over all the tropical parts of the region. Other important genera areCyclotusandMegalomastoma; whileCyclophorusalso occurs all over the region. The Helicinidæ are mostly Neotropical, six out of the seven genera being found here, and four are peculiar.Stoastoma, is one of the largest genera; and, withTrochatellaandAlcadia, is confined to the Antilles, while the wide-spreadHelicinais most abundant there.
The Limacidæ, or Old World slugs, are absent from the region, their place being taken by the allied family, Oncidiadæ.
Marine Shells.—We go out of our usual course to say a few words about the marine shells of this region, because their distribution on the two sides of the continent is important, as an indication of the former separation of North and South America, and the connection of the Atlantic and Pacific Oceans. It was once thought that no species of shells were common to the two sides of the Central American Isthmus, and Dr. Mörch still holds that opinion; but Dr. Philip Carpenter, who has paid special attention to the subject, considers that there are at least 35 species absolutely identical, while as many others are so close that they may be only varieties. Nearly 70 others are distinct but representative species. The genera of marine mollusca are very largely common to the east and west coasts, more than 40 being so named in the lists published by Mr. Woodward. The West Indian Islands being a rich shell district, produce a number of peculiar forms, and the west coast ofSouth America is, to some extent, peopled by Oriental and Pacific genera of shells. On the west coast there is hardly any coral, while on the east it is abundant, showing a difference of physical conditions that must have greatly influenced the development of mollusca. When these various counteracting influences are taken into consideration, the identity or close affinity of about 140 species and 40 genera on the two sides of the Isthmus of Panama becomes very important; and, combined with the fact of 48 species of fish (or 30 per cent. of those known) being identical on the adjacent coasts of the two oceans (as determined by Dr. Günther), render it probable that Central America has been partially submerged up to comparatively recent geological times. Yet another proof of this former union of two oceans is to be found in the fossil corals of the Antilles of the Miocene age, which Dr. Duncan finds to be more allied to existing Pacific forms, than to those of the Atlantic or even of the Caribbean Sea.
Neotropical Sub-regions.
In the concluding part of this work devoted to geographical zoology, the sub-regions are arranged in the order best adapted to exhibit them in a tabular form, and to show the affinities of the several regions; but for our present purpose it will be best to take first in order that which is the most important and most extensive, and which exhibits all the peculiar characteristics of the region in their fullest development. We begin therefore with our second division.
II. Tropical South-America, or the Brazilian Sub-region.
This extensive district may be defined as consisting of all the tropical forest-region of South America, including all the open plains and pasture lands, surrounded by, or intimately associated with, the forests. Its central mass consists of the great forest-plain of the Amazons, extending from Paranaiba on the north coast of Brazil (long. 42° W.) to Zamora, in the province of Loja (lat. 4° S., long. 79° W.), high up in the Andes, on the west;—a distance in a straight line of more than 2,500 English miles,along the whole of which there is (almost certainly) one continuous virgin forest. Its greatest extent from north to south, is from the mouths of the Orinooko to the eastern slopes of the Andes near La Paz in Bolivia and a little north of Sta. Cruz de la Sierra (lat. 18° S.), a distance of about 1,900 miles. Within this area of continuous forests, are included some open "campos," or patches of pasture lands, the most important being,—the Campos of the Upper Rio Branco on the northern boundary of Brazil; a tract in the interior of British Guiana; and another on the northern bank of the Amazon near its mouth, and extending some little distance on its south bank at Santarem. On the northern bank of the Orinooko are the Llanos, or flat open plains, partly flooded in the rainy season; but much of the interior of Venezuela appears to be forest country. The forest again prevails from Panama to Maracaybo, and southwards in the Magdalena valley; and on all the western side of the Andes to about 100 miles south of Guayaquil. On the N.E. coast of Brazil is a tract of open country, in some parts of which (as near Ceara) rain does not fall for years together; but south of Cape St. Roque the coast-forests of Brazil commence, extending to lat. 30° S., clothing all the valleys and hill sides as far inland as the higher mountain ranges, and even penetrating up the great valleys far into the interior. To the south-west the forest country reappears in Paraguay, and extends in patches and partially wooded country, till it almost reaches the southern extension of the Amazonian forests. The interior of Brazil is thus in the position of a great island-plateau, rising out of, and surrounded by, a lowland region of ever-verdant forest. The Brazilian sub-region comprises all this forest-country and its included open tracts, and so far beyond it as there exists sufficient woody vegetation to support its peculiar forms of life. It thus extends considerably beyond the tropic in Paraguay and south Brazil; while the great desert of Chaco, extending from 25° to 30° S., lat. between the Parana and the Andes, as well as the high plateaus of the Andean range, with the strip of sandy desert on the Pacific coast as far as to about 5° of south latitude, belong to south temperate America, or the sub-region of the Andes.
Having already given a sketch, of the zoological features of the Neotropical region as a whole, the greater part of which will apply to this sub-region, we must here confine ourselves to an indication of the more important groups which, on the one hand, are confined to it, and on the other are absent; together with a notice of its special relations to other regions.
Mammalia.—Many of the most remarkable of the American monkeys are limited to this sub-region; asLagothrix,Pithecia, andBrachyurus, limited to the great Amazonian forests;Eriodesto south-east Brazil; andCallithrixto tropical South America. All the marmosets (Hapalidæ) are also confined to this sub-region, one only being found at Panama, and perhaps extending a little beyond it. Among other peculiar forms, are 8 genera of bats; 3 peculiar forms of wild dog;Pteronura, a genus of otters;Inia, a peculiar form of dolphin inhabiting the upper waters of the Amazon; tapirs of the genusTapirus(a distinct genus being found north of Panama); 4 genera of Muridæ;Ctenomys, a genus of Octodontidæ; the whole family of Echimyidæ, or spiny rats, (as far as the American continent is concerned) consisting of 8 genera and 28 species;Chætomys, a genus of Cercolabidæ; the capybara (Hydrochœrus) the largest known rodent, belonging to the Caviidæ; the larger ant-eaters (Myrmecophaga); sloths of the genusBradypus; 2 genera of armadillos (Dasypodidæ); and two peculiar forms of the opossum family (Didelphyidæ). No group that is typically Neotropical is absent from this sub-region, except such as are peculiar to other single sub-regions and which will be noticed accordingly. The occurrence of a solitary species of hare (Lepus braziliensis) in central Brazil and the Andes, is remarkable, as it is cut off from all its allies, the genus not being known to occur elsewhere on the continent further south than Costa Rica. The only important external relation indicated by the Mammalia of this sub-region is towards the Ethiopian region, 2 genera of Echimyidæ,AulacodesandPetromys, occurring in South and South-east Africa.
Plate IV. Characteristic Neotropical Mammalia.—Our illustration represents a mountainous forest in Brazil, the part of South America where the Neotropical Mammalia are perhaps bestdeveloped. The central and most conspicuous figure is the collared ant-eater, (Tamandua tetradactyla), one of the handsomest of the family, in its conspicuous livery of black and white. To the left are a pair of sloths (Arctopithecus flaccidus) showing the curious black spot on the back with which many of the species are marked, and which looks like a hole in the trunk of a tree; but this mark seems to be only found on the male animal. The fur of many of the sloths has a greenish tinge, and Dr. Seemann remarked its resemblance to theTillandsia usneoides, or "vegetable horsehair," which clothes many of the trees in Central America; and this probably conceals them from their enemies, the harpy-eagles. On the right are a pair of opossums (Didelphys azaræ), one of them swinging by its prehensile tail. Overhead in the foreground are a group of howling monkeys (Mycetes ursinus) the largest of the American Quadrumana, and the noisiest of monkeys. The large hollow vessel into which the hyoid bone is transformed, and which assists in producing their tremendous howling, is altogether unique in the animal kingdom. Below them, in the distance, are a group of Sapajou monkeys (Cebussp.); while gaudy screaming macaws complete the picture of Brazilian forest life.
Birds.—A very large number of genera of birds, and some entire families, are confined to this sub-region, as will be seen by looking over the list of genera at the end of this chapter. We can here only notice the more important, and summarize the results. More than 120 genera of Passeres are thus limited, belonging to the following 12 families: Sylviidæ (1), Troglodytidæ (2), Cœrebidæ (4), Tanagridæ (26), Fringillidæ (8), Icteridæ (5), Pteroptochidæ (3), Dendrocolaptidæ (12), Formicariidæ (16), Tyrannidæ (22), Cotingidæ (16), Pipridæ (10). Of the Picariæ there are 76 peculiar genera belonging to 9 families, viz., Picidæ (2), Rhamphastidæ (1), Cuculidæ (1), Bucconidæ (2), Galbulidæ (5), Momotidæ (2), Podargidæ (1), Caprimalgidæ (4), Trochilidæ (58). There are 3 peculiar genera of Psittaci, 8 of Gallinæ, the only genus of Opisthocomidæ, 3 of Accipitres, 1 of Rallidæ,PsophiaandEurypygatypes of distinct families, and 1 genus of Ardeidæ, Palamedeidæ, and Anatidæ respectively. The preceding enumeration shows how very rich this sub-region is in peculiar types of all the most characteristic American families, such as the Tanagridæ, Tyrannidæ, Cotingidæ, Formicariidæ, Trochilidæ, and Galbulidæ. A considerable proportion of the genera of the Chilian and Mexican sub-regions also occur here, so that out of about 680 genera of Neotropical land-birds more than 500 are represented in this sub-region.
Plate XIV.
A BRAZILIAN FOREST, WITH CHARACTERISTIC MAMMALIA.
A BRAZILIAN FOREST, WITH CHARACTERISTIC MAMMALIA.
Without entering minutely into the distribution of species it is difficult to sub-divide this extensive territory with any satisfactory result.[1]The upland tract between the Amazon and Orinooko, which may be termed Guiana, was evidently once an island, yet it possesses few marked distinctive features. Brazil, which must have formed another great island, has more speciality, but the intermediate Amazonian forests form a perfect transition between them. The northern portion of the continent west of the Orinooko has more character; and there are indications that this has received many forms from Central and North America, and thus blended two faunas once more distinct than they are now. The family of wood-warblers (Mniotiltidæ) seems to have belonged to this more northern fauna; for out of 18 genera only 5 extend south of the equator, while 6 range from Mexico or the Antilles into Columbia, some of these being only winter immigrants and no genus being exclusively South American. The eastern slopes of the Andes constitute, however, the richest and best marked province of this sub-region. At least 12 genera of tanagers (Tanagridæ) are found here only, with an immense number of Fringillidæ,—the former confined to the forests; the latter ranging to the upland plains. The ant-thrushes (Formicariidæ) on the other hand seem more abundant in the lowlands, many genera being peculiar to the Amazonian forests. The superb chatterers (Cotingidæ) also seem to have their head-quarters in the forests of Brazil and Guiana, and to have thence spreadinto the Amazonian valley. Guiana still boasts such remarkable forms as the cardinal chatterer (Phœnicocercus), the military chatterer (Hæmatoderus), as well asQuerula,Gymnoderus, andGymnocephalus; but the first three pass to the south side of the Lower Amazon. Here also belong the cock of the rock (Rupicola), which ranges from Guiana to the Andes, and the marvellous umbrella-birds of the Rio Nigro and Upper Amazon (Cephalopterus), which extends across the Ecuadorean Andes and into Costa Rica. Brazil hasPtilochloris,Casiornis,Tijuca,Phibalura, andCalyptura; while not a single genus of this family, except perhapsHeliochæra, is confined to the extensive range of the Andes. Almost the same phenomena are presented by the allied Pipridæ or manakins, the greater part of the genera and species occurring in Eastern South America, that is in Brazil, Guiana, and the surrounding lowlands rather than in the Andean valleys. The same may be said of the jacamars (Galbulidæ) and puff-birds (Bucconidæ); but the humming-birds (Trochilidæ) have their greatest development in the Andean district. Brazil and Guiana have each a peculiar genus of parrots; Guiana has three peculiar genera of Cracidæ, while the Andes north of the equator have two. The Tinamidæ on the other hand have their metropolis in Brazil, which has two or three peculiar genera, while two others seem confined to the Andes south of the equator. The elegant trumpeters (Psophiidæ) are almost restricted to the Amazonian valley.
Somewhat similar facts occur among the Mammalia. At least 3 genera of monkeys are confined to the great lowland equatorial forests and 1 to Brazil;Icticyon(Canidæ) andPteronura(Mustelidæ) belong to Guiana and Brazil; and most of the Echimyidæ are found in the same districts. The sloths, ant-eaters, and armadillos all seem more characteristic of the eastern districts than of the Andean; while the opossums are perhaps equally plentiful in the Andes.
The preceding facts of distribution lead us to conclude that the highlands of Brazil and of Guiana represent very ancient lands, dating back to a period long anterior to the elevation of the Andean range (which is by no means of great geologicalantiquity) and perhaps even to the elevation of the continuous land which forms the base of the mountains. It was, no doubt, during their slow elevation and the consequent loosening of the surface, that the vast masses of debris were carried down which filled up the sea separating the Andean chain from the great islands of Brazil and Guiana, and formed that enormous extent of fertile lowland forest, which has created a great continent; given space for the free interaction of the distinct faunas which here met together, and thus greatly assisted in the marvellous development of animal and vegetable life, which no other continent can match. But this development, and the fusion of the various faunas into one homogeneous assemblage must have been a work of time; and it is probable that most of the existing continent was dry land before the Andes had acquired their present altitude. The blending of the originally distinct sub-faunas has been no doubt assisted by elevations and depressions of the land or of the ocean, which have alternately diminished and increased the land-area. This would lead to a crowding together at one time, and a dispersion at others, which would evidently afford opportunity for many previously restricted forms to enter fresh areas and become adapted to new modes of life.
From the preceding sketch it will appear, that the great sub-region of Tropical South America as here defined, is really formed of three originally distinct lands, fused together by the vast lowland Amazonian forests. In the class of birds sufficient materials exist for separating these districts; and that of the Andes contains a larger series of peculiar genera than either of the other sub-regions here adopted. But there are many objections to making such a sub-division here. It is absolutely impossible to define even approximate limits to these divisions—to say for example where the "Andes" ends and where "Brazil" or "Amazonia" or "Guiana" begins; and the unknown border lands separating these are so vast, that many groups, now apparently limited in their distribution, may prove to have a very much wider range. In mammalia, reptiles, and insects, it is even more difficult to maintain such divisions, so that on the whole it seems better to treat the entire area as one sub-region,although recognizing the fact of its zoological and geographical diversity, as well as its vast superiority over every other sub-region in the number and variety of its animal forms.
The reptiles, fishes, mollusca, and insects of this sub-region have been sufficiently discussed in treating of the entire region, as by far the larger proportion of them, except in the case of land-shells, are found here.
Plate XV. Characteristic Neotropical Birds.—To illustrate the ornithology of South America we place our scene on one of the tributaries of the Upper Amazon, a district where this class of animals is the most prominent zoological feature, and where a number of the most remarkable and interesting birds are to be found. On the left we have the umbrella-bird (Cephalopterus ornatus), so called from its wonderful crest, which, when expanded, completely overshadows its head like an umbrella. It is also adorned with a long tassel of plumes hanging from its breast, which is formed by a slender fleshy tube clothed with broad feathers. The bird is as large as a crow, of a glossy blue-black colour, and belongs to the same family as the exquisitely tinted blue-and-purple chatterers. Flying towards us are a pair of curl-crested toucans (Pteroglossus beauharnaisii), distinguished among all other toucans by a crest composed of small black and shining barbless plumes, resembling curled whalebone. The general plumage is green above, yellow and red beneath, like many of its allies. To the right are two of the exquisite little whiskered hummers, or "frill-necked coquettes," as they are called by Mr. Gould, (Lophornis gouldi). These diminutive birds are adorned with green-tipped plumes springing from each side of the throat, as well as with beautiful crests, and are among the most elegant of the great American family of humming-birds, now numbering about 400 known species. Overhead are perched a pair of curassows (Crax globulosa), which represent in America the pheasants of the Old World. There are about a dozen species of these fine birds, most of which are adorned with handsome curled crests. That figured, is distinguished by the yellow caruncular swellings at the base of the bill. The tall crane-like bird near the water is one of the trumpeters, (Psophia leucoptera), elegant 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.
Plate XV.
A FOREST SCENE ON THE UPPER AMAZON, WITH SOME CHARACTERISTIC BIRDS.
A FOREST SCENE ON THE UPPER AMAZON, WITH SOME CHARACTERISTIC BIRDS.
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. We must therefore notice them in some detail.
Mammalia.—This class is represented by a mouse belonging to the American genusHesperomys, 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, somewhatchanged under its new conditions of life (the genusMusnot 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.[2]—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 plumbeaandNycticorax pauper); a flamingo (Phœnicopterus 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 onlyspeciesnot 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,—andAsio accipitrinus, an owl which is found almost all over the world. The only genera not exclusively American areButeoandStrix, 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.Dendrœca, 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 oftropical 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 theCœrebidæ, 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 toT. 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 nearestto the mainland. Taking the six islands which seem tolerably explored, we find that two of the species (Dendrœca aureolaandGeospiza fortis) occur in all of them; two others (Geospiza strenuaandMyiarchus magnirostris) in five; four (Mimus melanotis,Geospiza fuliginosa,G. parvula, andCamarhynchus 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. habeliandAsio 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 genusHerpetodryas, 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 ofPhyllodactylus, a wide-spread genus of Geckotidæ; the rest belong to the American family of the Iguanas, one being a species of the Neotropical genusLeiocephalus, the other two very remarkable forms,TrachycephalusandOreocephalus(formerly united in the genusAmblyrhynchus). 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 lastreptile 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, aCalosoma,Pœcilus,Solenophorus, andNotaphus, among the Carabidæ; anOryctesamong the Lamellicornes; two new genera of obscure Heteromera; two Curculionidæ of wide-spread genera; a Longicorn of the South American genusEburia; 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 ofBulimulus, a genus greatly developed on the whole West coast of America; and a single species ofBuliminus, 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 peculiargeneraconsist of birds and lizards, which must therefore have been the earliestimmigrants. We know that small Passerine birds annually reach the Bermudas from America, and the Azores from Europe, the former travelling over 600, the latter over 1000 miles of ocean. These groups of islands are both situated in stormy seas, and the immigrants are so numerous that hardly any specific change in the resident birds has taken place. The Galapagos receive no such annual visitants; hence, when by some rare accident a few individuals of a species did arrive, they remained isolated, probably for thousands of generations, and became gradually modified through natural selection under completely new conditions of existence. Less rare and violent storms would suffice to carry some of these to other islands, and thus the archipelago would in time become stocked. It would appear probable, that those which have undergone most change were the earliest to arrive; so that we might look upon the three peculiar genera of finches, andCerthidea, the peculiar form of Cœrebidæ, as among the most ancient inhabitants of the islands, since they have become so modified as to have apparently no near allies on the mainland. But other birds may have arrived nearly at the same time, and yet not have been much changed. A species of very wide range, already adapted to live under very varied conditions and to compete with varied forms of life, might not need to become modified so much as a bird of more restricted range, and more specialized constitution. And if, before any considerable change had been effected, a second immigration of the same species occurred, crossing the breed would tend to bring back the original type of form. While, therefore, we may be sure that birds like the finches, which are profoundly modified and adapted to the special conditions of the climate and vegetation, are among the most ancient of the colonists; we cannot be sure that the less modified form of tyrant-flycatcher or mocking-thrush, or even the unchanged but cosmopolitan owl, were not of coeval date; since even if the parent form on the continent has been changed, successive immigrations may have communicated the same change to the colonists.
The reptiles are somewhat more difficult to account for. We know, however, that lizards have some means of dispersal overthe sea, because we find existing species with an enormous range. The ancestors of theAmblyrhynchimust have come as early, probably, as the earliest birds; and the same powers of dispersal have spread them over every island. The two American genera of lizards, and the tortoises, are perhaps later immigrants. Latest of all were the snakes, which hardly differ from continental forms; but it is not at all improbable that these latter, as well as the peculiar American mouse, have been early human importations. Snakes are continually found on board native canoes whose cabins are thatched with palm leaves; and a few centuries would probably suffice to produce some modification of a species completely isolated, under conditions widely different from those of its native country. Land-shells, being so few and small, and almost all modifications of one type, are a clear indication of how rare are the conditions which lead to their dispersal over a wide extent of ocean; since two or three individuals, arriving on two or three occasions only during the whole period of the existence of the islands, would suffice to account for the present fauna. Insects have arrived much more frequently; and this is in accordance with their habits, their lower specific gravity, their power of flight, and their capacity for resisting for some time the effects of salt water.
We learn, then, from the fauna of these islands, some very important facts. We are taught that tropical land-birds, unless blown out of their usual course by storms, rarely or never venture out to sea, or if they do so, can seldom pass safely over a distance of 500 miles. The immigrants to the Galapagos can hardly have averaged a bird in a thousand years. We learn, that of all reptiles lizards alone have some tolerably effective mode of transmission across the sea; and this is probably by means of currents, and in connection with floating vegetation. Yet their transmission is a far rarer event than that of land-birds; for, whereas three female immigrants will account for the lizard population, at least eight or ten ancestors are required for the birds. Land serpents can pass over still more rarely, as two such transmissions would have sufficed to stock the islands with their snakes; and it is not certain that either of these occurred without the aid of man.It is doubtful whether mammals or batrachians have any means of passing, independently of man's assistance; the former having but one doubtfully indigenous representative, the latter none at all. The remarkable absence of all gay or conspicuous flowers in these tropical islands, though possessing a zone of fairly luxuriant shrubby vegetation, and the dependence of this phenomenon on the extreme scarcity of insects, has been already noticed at Vol. I. p. 461, when treating of a somewhat similar peculiarity of the New Zealand fauna and flora.
I. South Temperate America, or the Chilian Sub-region.
This sub-region may be generally defined as the temperate portion of South America. On the south, it commences with the cold damp forests of Tierra del Fuego, and their continuation up the west coast to Chiloe and northward to near Santiago. To the east we have the barren plains of Patagonia, gradually changing towards the north into the more fertile, but still treeless, pampas of La Plata. Whether this sub-region should be continued across the Rio de la Plata into Uruguay and Entre-rios, is somewhat doubtful. To the west of the Parana it extends northward over the Chaco desert, till we approach the border of the great forests near St. Cruz de la Sierra. On the plateau of the Andes, however, it must be continued still further north, along the "paramos" or alpine pastures, till we reach 5° of South latitude. Beyond this the Andes are very narrow, having no double range with an intervening plateau; and although some of the peculiar forms of the temperate zone pass on to the equator or even beyond it, these are not sufficiently numerous to warrant our extending the sub-region to include them. Along with the high Andes it seems necessary to include the western strip of arid country, which is mostly peopled by forms derived from Chili and the south temperate regions.
Mammalia.—This sub-region is well characterised by the possession of an entire family of mammalia having Neotropical affinities—the Chinchillidæ. It consists of 3 genera—Chinchilla(2 sp.), inhabiting the Andes of Chili and Peru as far as 9° south latitude, and at from 8,000 to 12,000 feet altitude;Lagidium(3 sp.), ranging over the Andes of Chili, Peru, and South Ecuador,from 11,000 to 16,000 feet altitude; andLagostomus(1 sp.), the "viscacha," confined to the pampas between the Uruguay and Rio Negro. Many important genera are also confined to this sub-region.Auchenia(4 sp.), including the domesticated llamas and alpacas, the vicugna which inhabits the Andes of Peru and Chili, and the guanaco which ranges over the plains of Patagonia and Tierra del Fuego. Although this genus is allied to the Old World camels, it is a very distinct form, and its introduction from North America, where the family appear to have originated, may date back to a remote epoch.Ursus ornatus, the "spectacled bear" of the Chilian Andes, is a remarkable form, supposed to be most allied to the Malay bear, and probably forming a distinct genus, which has been namedTremarctos. Four genera of Octodontidæ are also peculiar to this sub-region, or almost so;Habrocomus(1 sp.) is Chilian;Spalacopus(2 sp.) is found in Chili and on the east side of the southern Andes;Octodon(3 sp.) ranges from Chili into Peru and Bolivia;Ctenomys(6 sp.) from the Straits of Magellan to Bolivia, with one species in South Brazil.Dolichotis, one of the Cavies, ranges from Patagonia to Mendoza, and on the east coast to 37½° S. latitude.Myopotamus(1 sp.), the coypu (Echimyidæ), ranges from 33° to 48° S. latitude on the west side of the Andes, and from the frontiers of Peru to 42° S. on the east side.ReithrodonandAcodon, genera of Muridæ, are also confined to Temperate South America;TolypeutesandChlamydophorus, two genera of armadillos, the latter very peculiar in its organization and sometimes placed in a distinct family, are found only in La Plata and the highlands of Bolivia, and so belong to this sub-region.Otaria, one of the "eared seals" (Otariidæ), is confined to the coasts of this sub-region and the antarctic islands. Deer of American groups extend as far as Chiloe on the west, and the Straits of Magellan on the east coast. Mice of the South American generaHesperomysandReithrodon, are abundant down to the Straits of Magellan and into Tierra del Fuego, Mr. Darwin having collected more than 20 distinct species. The following are the genera of Mammalia which have been observed on the shores of the Straits of Magellan, those marked * extending into Tierra del Fuego:*Pseudalopex(two wolf-like foxes),Felis(the puma),Mephitis(skunks),Cervus(deer), *Auchenia(guanaco), *Ctenomys(tucu-tucu), *Reithrodonand *Hesperomys(American mice).
Birds.—Three families of Birds are confined to this sub-region,—Phytotomidæ (1 genus, 3 sp.), inhabiting Chili, La Plata, and Bolivia; Chionididæ (1 genus, 2 sp.) the "sheath-bills," found only at the southern extremity of the continent and in Kerguelen's Island, which with the other antarctic lands perhaps comes best here; Thinocoridæ (2 genera, 6 species) an isolated family of waders, ranging over the whole sub-region and extending northward to the equatorial Andes. Many genera are also peculiar: 3 of Fringillidæ, and 1 of Icteridæ; 9 of Dendrocolaptidæ, 6 of Tyrannidæ, 3 of Trochilidæ, and 4 of Pteroptochidæ,—the last four South American families. There is also a peculiar genus of parrots (Henicognathus) in Chili; two of pigeons (MetriopeliaandGymnopelia) confined to the Andes and west coast from Peru to Chili; two of Tinamous,Tinamotesin the Andes, andCalodromusin La Plata; three of Charadriidæ,Phægornis,Pluvianellus, andOreophilus; andRhea, the American ostriches, inhabiting all Patagonia and the pampas. Perhaps the Cariamidæ have almost as much right here as in the last sub-region, inhabiting as they do, the "pampas" of La Plata and the upland "campos" of Brazil; and even among the wide-ranging aquatic birds, we have a peculiar genus,Merganetta, one of the duck family, which is confined to the temperate plateau of the Andes.
Against this extensive series of characteristic groups, all either of American type or very distinct forms of Old World families, and therefore implying great antiquity, we find, in mammalia and birds, very scanty evidence of that direct affinity with the north temperate zone, on which some naturalists lay so much stress. We cannot point to a single terrestrial genus, which is characteristic of the north and reappears in this south temperate region without also occurring over much of the intervening land.Mustelaseems only to have reached Peru;Lepusis isolated in Brazil; trueUrsusdoes not pass south of Mexico. In birds, the northern groups rarely go further south than Mexico or the Columbian Andes; and the only case of discontinuousdistribution we can find recorded is that of the genus of ducks,Camptolæmus, which has a species on the east side of North America and another in Chili and the Falkland Islands, but these, Professor Newton assures me, do not properly belong to the same genus. Out of 30 genera of land-birds collected on the Rio Negro in Patagonia, by Mr. Hudson, only four extend beyond the American continent, and the same exclusively American character applies equally to its southern extremity. No list appears to have been yet published of the land-birds of the Straits of Magellan and Tierra del Fuego. The following is compiled from the observations of Mr. Darwin, the recent voyage of Professor Cunningham, and other sources; and will be useful for comparison.