Chapter XI: Part III: (continued.) (2)

_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.

{29}_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 genus _Hesperomys_, 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 {30}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._[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 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. _Dendroeca_, 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 {31}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 _Coerebidæ_, 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 {32}to the mainland. Taking the six islands which seem tolerably explored, we find that two of the species (_Dendroeca aureola_ and _Geospiza 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 {33}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_, _Poecilus_, _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 {34}immigrants. 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, and _Certhidea_, the peculiar form of Coerebidæ, 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 over {35}the sea, because we find existing species with an enormous range. The ancestors of the _Amblyrhynchi_ must 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. {36}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, {37}from 11,000 to 16,000 feet altitude; and _Lagostomus_ (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 named _Tremarctos_. 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. _Reithrodon_ and _Acodon_, genera of Muridæ, are also confined to Temperate South America; _Tolypeutes_ and _Chlamydophorus_, 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 genera _Hesperomys_ and _Reithrodon_, 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: {38}*_Pseudalopex_ (two wolf-like foxes), _Felis_ (the puma), _Mephitis_ (skunks), _Cervus_ (deer), *_Auchenia_ (guanaco), *_Ctenomys_ (tucu-tucu), *_Reithrodon_ and *_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 (_Metriopelia_ and _Gymnopelia_) confined to the Andes and west coast from Peru to Chili; two of Tinamous, _Tinamotes_ in the Andes, and _Calodromus_ in La Plata; three of Charadriidæ, _Phægornis_, _Pluvianellus_, and _Oreophilus_; and _Rhea_, 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. _Mustela_ seems only to have reached Peru; _Lepus_ is isolated in Brazil; true _Ursus_ does 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 discontinuous {39}distribution 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.

TURDIDÆ.
1. Turdus falklandicus.

TROGLODYTIDÆ.
2. Troglodytes magellanicus.

FRINGILLIDÆ.
3. Chrysomitris barbata.
*4. Phrygilus gayi.
*5. " aldunatii.
6. " fruticeti.
*7. " xanthogrammus.
8. Zonotrichia pileata.

ICTERIDÆ.
9. Sturnella militaris.
10. Curæus aterrimus.

HIRUNDINIDÆ.
11. Hirundo meyeni.

TYRANNIDÆ.
12. Tænioptera pyrope.
13. Myiotheretes rufiventris.
14. Muscisaxicola mentalis.
15. Centrites niger.
16. Anæretes parulus.
17. Elainea griseogularis.

DENDROCOLAPTIDÆ.
18. Upucerthia dumetoria.
*19. Cinclodes patagonicus.
*20. " fuscus.
*21. Oxyurus spinicauda.

PTEROPTOCHIDÆ.
*22. Scytalopus magellanicus.

PICIDÆ.
*23. Campephilus magellanicus.
24. Picus lignarius.

ALCEDINIDÆ.
25. Ceryle stellata.

TROCHILIDÆ.
26. Eustephanus galeritus.

CONURIDÆ.
27. Conurus patagonus.

VULTURIDÆ.
28. Cathartes aura.
29. Sarcorhamphus gryphus.

FALCONIDÆ.
30. Circus macropterus.
31. Buteo erythronotus.
32. Geranoaëtus melanolencus.
33. Accipiter chilensis.
34. Cerchneis sparverius.
35. Milvago albogularis.
36. Polyborus tharus.

STRIGIDÆ.
37. Asio accipitrinus.
38. Bubo magellanicus.
39. Pholeoptynx cunicularia.
40. Glaucidium nana.
41. Syrnium rufipes.

STRUTHIONIDÆ.
42. Rhea darwinii.

{40}In the above list the species marked * extend to Tierra del Fuego. It is a remarkable fact that so many of the species belong to genera which are wholly Neotropical, and that the specially South American families of Icteridæ, Tyrannidæ, Dendrocolaptidæ, Pteroptochidæ, Trochilidæ, and Conuridæ, should supply more than one-third of the species; while the purely South American genus _Phrygilus_, should be represented by four species, three of which abound in Tierra del Fuego.

_Plate XVI. A Scene in the Andes of Chili, with characteristic Animals._--The fauna of South Temperate America being most fully developed in Chili, we place the scene of our illustration in that country. In the foreground we have a pair of the beautiful little chinchillas (_Chinchilla lanigera_), belonging to a family of animals peculiar to the sub-region. There are only two species of this group, both confined to the higher Andes, at about 8000 feet elevation. Coming round a projecting ridge of the mountain, are a herd of vicunas (_Auchenia vicugna_), one of that peculiar form of the camel tribe found in South America and confined to its temperate and alpine regions. The upper bird is a plant-cutter (_Phytotoma rara_), of sober plumage but allied to the beautiful chatterers, though forming a separate family. Below, standing on a rock, is a plover-like bird, the _Thinocorus orbignianus_, which is considered to belong to a separate family, though allied to the plovers and sheath-bills. Its habits are, however, more those of the quails or partridges, living inland in dry and desert places, and feeding on plants, roots, and insects. Above is a condor, the most characteristic bird of the high Andes.

_Reptiles and Amphibia._--These groups show, for the most part, similar modifications of American and Neotropical forms, as those we have seen to prevail among the birds. Snakes do not seem to go very far south, but several South American genera of Colubridæ and Dendrophidæ occur in Chili; while _Enophrys_ is peculiar to La Plata, and _Callorhinus_ to Patagonia, both belonging to the Colubridæ. The Elapidæ do not extend into the temperate zone; but _Craspedocephalus_, one of the Crotalidæ, occurs at Bahia Blanca in Patagonia (Lat. 40° S.)

Plate XVI.

THE CHILIAN ANDES, WITH CHARACTERISTIC ANIMALS.

{41}Lizards are much more numerous, and there are several peculiar and interesting forms. Three families are represented; Teidæ by two genera--_Callopistes_ peculiar to Chili, and _Ameiva_ which ranges over almost the whole American continent and is found in Patagonia; _Geckotidæ_ by four genera, two of which,--_Caudiverbera_ and _Homonota_--are peculiar to Chili, while _Sphærodactylus_ and _Cubina_ are Neotropical, the former ranging to Patagonia, the latter to Chili; and lastly the American family Iguanidæ represented by eight genera, no less than six being peculiar, (or almost so,) to the South temperate region. These are _Leiodera_, _Diplolæmus_ and _Proctrotretus_, ranging from Chili to Patagonia; _Leiolæmus_, from Peru to Patagonia; _Phrymaturus_, confined to Chili, and _Ptygoderus_ peculiar to Patagonia and Tierra del Fuego. The other two genera, _Oplurus_ and _Leiosaurus_, are common to Chili and tropical South America.

Tortoises appear to be scarce, a species of _Hydromedusa_ only being recorded. Of the Amphibia, batrachia (frogs and toads) alone are represented, and appear to be tolerably abundant, seventeen species having been collected by Mr. Darwin in this sub-region. Species of the South American genera _Phryniscus_, _Hylaplesia_, _Telmatobius_, _Cacotus_, _Hylodes_, _Cyclorhamphus_, _Pleurodema_, _Cystignathus_, and _Leiuperus_, are found in various localities, some extending even to the Straits of Magellan,---the extreme southern limit of both Reptilia and Amphibia, except one lizard (_Ptygoderus_) found by Professor Cunningham in Tierra del Fuego. There are also four peculiar genera, _Rhinoderma_ belonging to the Engystomidæ; _Alsodes_ and _Nannophryne_ to the Bombinatoridæ; _Opisthodelphys_ to the Hylidæ; and _Calyptocephalus_ to the Discoglossidæ.

It thus appears, that in the Reptiles all the groups are typically American, and that most of the peculiar genera belong to families which are exclusively American. The Amphibia, on the other hand, present some interesting external relations, but these are as much with Australia as with the North temperate regions. The Bombinatoridæ are indeed Palæarctic, but a larger proportion are Neotropical, and one genus inhabits New Zealand. The Chilian genus _Calyptocephalus_ is allied to Australian tropical genera. {42}The Neotropical genera of Ranidæ, five of which extend to Chili and Patagonia, belong to a division which is Australian and Neotropical, and which has species in the Oriental and Ethiopian regions.

_Fresh-water Fishes._--These present some peculiar forms, and some very interesting phenomena of distribution. The genus _Percilia_ has been found only in the Rio de Maypu in Chili; and _Percichthys_, also belonging to the perch family, has five species confined to the fresh waters of South Temperate America, and one far away in Java. _Nematogenys_ (1 sp.) is peculiar to Chili; _Trichomycterus_ reaches 15,000 feet elevation in the Andes,--both belonging to the Siluridæ; _Chirodon_ (2 sp.), belonging to the Characinidæ, is peculiar to Chili; and several other genera of the same family extend into this sub-region from Brazil. The family _Haplochitonidæ_ has a remarkable distribution; one of its genera, Haplochiton (2 sp.), inhabiting Tierra del Fuego and the Falkland Islands, while the other, _Prototroctes_, is found only in South Australia and New Zealand. Still more remarkable is _Galaxias_ (forming the family Galaxidæ), the species of which are divided between Temperate South America, and Australia, Tasmania, and New Zealand; and there is even one species (_Galaxias attenuatus_) which is found in the Chatham Islands, New Zealand, and Tasmania, as well as in the Falkland Islands and Patagonia. _Fitzroya_ (1 sp.) is found only at Montevideo; _Orestias_ (6 sp.) is peculiar to Lake Titicaca in the high Andes of Bolivia; _Jenynsia_ (1 sp.) in the Rio de la Plata--all belonging to the characteristic South American family of the Cyprinodontidæ.

_Insects._--It is in insects more than in any other class of animals, that we find clear indications of a not very remote migration of northern forms, along the great mountain range to South Temperate America, where they have established themselves as a prominent feature in the entomology of the country. The several orders and families, however, differ greatly in this respect; and there are some groups which are only represented by modifications of tropical forms, as we have seen to be almost entirely the case in birds and reptiles.

{43}_Lepidoptera._--The butterflies of the South Temperate Sub-region are not numerous, only about 29 genera and 80 species being recorded. Most of these are from Chili, which is sufficiently accounted for by the general absence of wood on the east side of the Andes from Buenos Ayres to South Patagonia. The families represented are as follows: Satyridæ, with 11 genera and 27 species, are the most abundant; Nymphalidæ, 2 genera and 8 species; Lemoniidæ, 1 genus, 1 species; Lycænidæ, 3 genera, 8 species; Pieridæ, 6 genera, 14 species; Papilionidæ, 2 genera, 8 species; Hesperidæ, 4 genera, 13 species. One genus of Satyridæ (_Elina_) and 2 of Pieridæ (_Eroessa_ and _Phulia_) are peculiar to Chili. The following are the genera whose derivation must be traced to the north temperate zone:--_Tetraphlybia_, _Neosatyrus_, and 3 allied genera of 1 species each, were formerly included under _Erebia_, a northern and arctic form, yet having a few species in South Africa; _Argyrophorus_, allied to _Æneis_, a northern genus; _Hipparchia_, a northern genus yet having a species in Brazil;--all Satyridæ. The Nymphalidæ are represented by the typical north temperate genus _Argynnis_, with 7 species in Chili; _Colias_, among the Pieridæ, is usually considered to be a northern genus, but it possesses representatives in South Africa, the Sandwich Islands, Malabar, New Grenada, and Peru, as well as Chili, and must rather be classed as cosmopolitan. These form a sufficiently remarkable group of northern forms, but they are accompanied by others of a wholly Neotropical origin. Such are _Stibomorpha_ with 6 species, ranging through South America to Guatemala, and _Eteona_, common to Chili and Brazil (Satyridæ); _Apodemia_ (Lemoniidæ) confined to Tropical America and Chili. _Hesperocharis_ and _Callidryas_ (Pieridæ), both tropical; and _Thracides_ (Hesperidæ) confined to Tropical America and Chili. Other genera are widely scattered; as, _Epinephile_ found also in Mexico and Australia; _Cupido_, widely spread in the tropics; _Euryades_, found only in La Plata and Paraguay, allied to South American forms of _Papilio_, to the Australian _Eurycus_, and the northern _Parnassius_; and _Heteropterus_, scattered in Chili, North America, and Tropical Africa. We find then, among butterflies, a large north-temperate element, {44}intermingled in nearly equal proportions with forms derived from Tropical America; and the varying degrees of resemblances of the Chilian to the northern species, seems to indicate successive immigrations at remote intervals.

_Coleoptera._--It is among the beetles of South Temperate America that we find some of the most curious examples of remote affinities, and traces of ancient migrations. The Carabidæ are very well represented, and having been more extensively collected than most other families, offer us perhaps the most complete materials. Including the Cicindelidæ, about 50 genera are known from the South Temperate Sub-region, the greater part from Chili, but a good number also from Patagonia and the Straits of Magellan. Of these more than 30 are peculiar, and most of them are so isolated that it is impossible to determine with precision their nearest allies.

The only remarkable form of Cicindelidæ is _Agrius_, a genus allied to the _Amblycheila_ and _Omus_ of N.W. America. Two genera of Carabidæ, _Cascellius_ and _Baripus_, are closely allied to _Promecoderus_, an Australian genus; and another, _Lecanomerus_, has one species in Chili and the other in Australia. Five or six of the peculiar genera are undoubtedly allied to characteristic Palæarctic forms; and such northern genera as _Carabus_, _Pristonychus_, _Anchomenus_, _Pterostichus_, _Percus_, _Bradycellus_, _Trechus_, and _Bembidium_, all absent from Tropical America, give great support to the view that there is a close relation between the insects of the northern regions and South Temperate America. A decided tropical element is, however, present. _Tropopterus_ is near _Colpodes_, a Tropical and South American genus; _Mimodromius_ and _Plagiotelium_ are near _Calleida_, a South American genus; while _Pachyteles_, _Pericompsus_, _Variopalpus_, and _Calleida_ are widely spread American groups. The preponderance of northern forms seems, however, to be undoubted.

Six Carabidæ are known from Juan Fernandez, 3 being identical with Chilian species and 3 peculiar. As the island is 350 miles from the mainland, we have here a proof of how readily insects may be transported great distances.

{45}The Palæarctic affinity of the South Temperate Carabidæ may be readily understood, if we bear in mind the great antiquity of the group, and the known long persistence of generic and specific forms of Coleoptera; the facility with which they may be transported to great distances by gales and hurricanes, either on land or over the sea; and, therefore, the probability that suitable stations would be rapidly occupied by species already adapted to them, to the exclusion of those of the adjacent tracts which had been specialised under different conditions. If, for example, we carry ourselves back to the time when the Andes had only risen to half their present altitude, and Patagonia had not emerged from the ocean (an epoch not very remote geologically), we should find nearly all the Carabidæ of South America, adapted to a warm, and probably forest-covered country. If, then, a further considerable elevation of the land took place, a large temperate and cold area would be formed, without any suitable insect inhabitants. During the necessarily slow process of elevation, many of the tropical Carabidæ would spread upwards, and some would become adapted to the new conditions; while the majority would probably only maintain themselves by continued fresh immigrations. But, as the mountains rose, another set of organisms would make their way along the highest ridges. The abundance and variety of the North Temperate Carabidæ, and their complete adaptation to a life on barren plains and rock-strewn mountains, would enable them rapidly to extend into any newly-raised land suitable to them; and thus the whole range of the Rocky Mountains and Andes would obtain a population of northern forms, which would overflow into Patagonia, and there, finding no competitors, would develope into a variety of modified groups. This migration was no doubt effected mainly, during successive glacial epochs, when the mountain-range of the Isthmus of Panama, if moderately increased in height, might become adapted for the passage of northern forms, while storms would often carry insects from peak to peak over intervening forest lowlands or narrow straits of sea. If this is the true explanation, we ought to find no such preponderant northern element in groups which {46}are proportionally less developed in cold and temperate climates. Our further examination will show how far this is the case.

Lucanidæ.--Only four genera are known in the sub-region. Two are peculiar, _Chiasognathus_ and _Streptocerus_, the former allied to Tropical American, the latter to Australian genera; the other two genera are exclusively South American.

Cetoniidæ.--These seem very scarce, only a few species of the Neotropical genus _Gymnetis_ reaching Patagonia.

Buprestidæ.--These are rather numerous, many very beautiful species being found in Chili. Nineteen genera are represented in South Temperate America, and 5 of these are peculiar to it; 3 others are South American genera; 2 are Australian, and the remainder are wide-spread, but all are found also in Tropical America. The only north-temperate genus is _Dicerca_, and even this occurs also in the Antilles, Brazil, and Peru. Of the peculiar genera, the largest, _Dactylozodes_ (26 sp.), has one species in South Brazil, and is closely allied to _Hyperantha_, a genus of Tropical America; _Epistomentis_ is allied to _Nascis_, an Australian genus; _Tyndaris_ is close to _Acmoeodera_, a genus of wide range and preferring desert or dry countries. The other two are single species of cosmopolitan affinities. On the whole, therefore, the Buprestidæ are unmistakeably Neotropical in character.

Longicorns.--Almost the whole of the South Temperate Longicorns inhabit Chili, which is very rich in this beautiful tribe. About 75 genera and 160 species are known, and nearly half of the genera are peculiar. Many of the species are large and handsome, rivalling in beauty those of the most favoured tropical lands. Of the 8 genera of Prionidæ 6 are peculiar, but all are allied to Tropical American forms except _Microplophorus_, which belongs to a group of genera spread over Australia, Europe, and Mexico. The Cerambycidæ are much more abundant, and their affinities more interesting. Two (_Syllitus_ and _Pseudocephalus_) are common to Australia and Chili. Twenty-three are Neotropical; and among these _Ibidion_, _Compsocerus_, _Callideriphus_, _Trachyderes_, and _Xylocharis_, are best represented. Twenty are {47}altogether peculiar, but most of them are more or less closely allied to genera inhabiting Tropical America. Some, as the handsome _Cheloderus_ and _Oxypeltus_, have no close allies in any part of the world. _Holopterus_, though very peculiar, shows most resemblance to a New Zealand insect. _Sibylla_, _Adalbus_, and _Phantagoderus_, have Australian affinities; while _Calydon_ alone shows an affinity for north-temperate forms. One species of the northern genus, _Leptura_, is said to have been found at Buenos Ayres.

The Lamiidæ are less abundant. Nine of the genera are Neotropical. Two (_Apomecyna_ and _Exocentrus_) are spread over all tropical regions. Ten genera are peculiar; and most of these are related to Neotropical groups or are of doubtful affinities. Only one, _Aconopterus_, is decidedly allied to a northern genus, _Pogonochærus_. It thus appears, that none of the Lamiidæ exhibit Australian affinities, although these are a prominent feature in the relations of the Cerambycidæ.

It is evident, from the foregoing outline, that the insects of South Temperate America, more than any other class of animals, exhibit a connection with the north temperate regions, yet this connection is only seen in certain groups. In Diurnal Lepidoptera and in Carabidæ, the northern element is fully equal to the tropical, or even preponderates over it. We have already suggested an explanation of this fact in the case of the Carabidæ, and with the butterflies it is not more difficult. The great mass of Neotropical butterflies are forest species, and have been developed for countless ages in a forest-clad tropical country. The north temperate butterflies, on the other hand, are very largely open-country species, frequenting pastures, mountains, and open plains, and often wandering over an extensive area. These would find, on the higher slopes of mountains, a vegetation and conditions suited to them, and would occupy such stations in less time than would be required to adapt and modify the forest-haunting groups of the American lowlands. In those groups of insects, however, in which the conditions of life are nearly the same as regards both temperate and tropical species, the superior {48}number and variety of the tropical forms has given them the advantage. Thus we find that among the Lucanidæ, Buprestidæ, and Longicorns, the northern element is hardly perceptible. Most of these are either purely Neotropical, or allied to Neotropical genera, with the admixture, however, of a decided Australian element. As in the case of the Amphibia and fresh-water fishes, the Australian affinity, as shown by insects, is of two kinds, near and remote. We have a few genera common to the two countries; but more commonly the genera are very distinct, and the affinity is shown by the genera of both countries belonging to a group peculiar to them, but which may be of very great age. In the former case, we must impute some of the resemblance of the two faunas to an actual interchange of forms within the epoch of existing genera--a period of vast and unknown duration in the class of insects; while in the latter case, and perhaps also in many of the former, it seems more in accordance with the whole of the phenomena, to look upon most of the instances as survivals, in the two southern temperate areas, of the relics of groups which had once a much wider distribution. That this is the true explanation, is suggested by the numerous cases of discontinuous and scattered distribution we have had to notice, in which every part of the globe, without exception, is implicated; and there is a reason why these survivals should be rather more frequent in Australia and temperate South America, inasmuch as these two areas agree in the absence of a considerable number of otherwise cosmopolitan vertebrate types, and are also in many respects very similar in climatic and other physical conditions. The preponderating influence of the organic over the physical environment, as taught by Mr. Darwin, leads us to give most weight to the first of the above-mentioned causes; to which we may also impute such undoubted cases of survival of ancient types as the Centetidæ of the Antilles and Madagascar--both areas strikingly deficient in the higher vertebrate forms. The probable mode and time of the cross migration between Australia and South America, has been sufficiently discussed in our chapter on the Australian region, when treating of the origin and affinities of the New Zealand fauna.

{49}_Islands of the South Temperate Sub-region._

These are few, and of not much zoological interest. Tierra del Fuego, although really an island, is divided from the mainland by so narrow a channel that it may be considered as forming part of the continent. The guanaco (_Auchenia huanaco_) ranges over it, and even to small islands further south.

_The Falkland Islands._--These are more important, being situated about 350 miles to the east of Southern Patagonia; but the intervening sea is shallow, the 100 fathom line of soundings passing outside the islands. We have therefore reason to believe that they have been connected with South America at a not distant epoch; and in agreement with this view we find most of their productions identical, while the few that are peculiar are closely allied to the forms of the mainland.

The only indigenous Mammals are a wolf-like fox (_Pseudalopex antarcticus_) said to be found nowhere else, but allied to two other species inhabiting Southern Patagonia; and a species of mouse, probably one of the American genera _Hesperomys_ or _Reithrodon_.

Sixty-seven species of Birds have been obtained in these islands, but only 18 are land-birds; and even of these 7 are birds of prey, leaving only 11 Passeres. The former are all common South American forms, but one species, _Milvago australis_, seems peculiar. The 11 Passeres belong to 9 genera, all found on the adjacent mainland. Three, or perhaps four, of the species are however peculiar. These are _Phrygilus melanoderus_, _P. xanthogrammus_, _Cinclodes antarcticus_, and _Muscisaxicola macloviana_. The wading and swimming birds are of little interest, except the penguins, which are greatly developed; no less than eight species being found, five as residents and three as accidental visitors.

No reptiles are known to inhabit these islands.

_Juan Fernandez._--This island is situated in the Pacific Ocean, about 400 miles west of Valparaiso in Chili. It is only a few miles in extent, yet it possesses four land-birds, excluding the powerful Accipitres. These are _Turdus falklandicus_; _Anæretes {50}fernandensis_, one of the Tyrannidæ; and two humming-birds, _Eustephanus fernandensis_ and _E. galeritus_. The first is a widespread South Temperate species, the two next are peculiar to the island, while the last is a Chilian species which ranges south to Tierra del Fuego. But ninety miles beyond this island lies another, called "Mas-a-fuero," very much smaller; yet this, too, contains four species of similar birds; one, _Oxyurus mas-a-fueræ_, allied to the wide-spread South Temperate _O. spinicauda_, and _Cinclodes fusus_, a South Temperate species--both Dendrocolaptidæ; with a humming-bird, _Eustephanus leyboldi_, allied to the species in the larger island. The preceding facts are taken from papers by Mr. Sclater in the _Ibis_ for 1871, and a later one in the same journal by Mr. Salvin (1875). The former author has some interesting remarks on the three species of humming-birds of the genus _Eustephanus_, above referred to. The Chilian species, _E. galeritus_, is green in both sexes. _E. fernandensis_ has the male of a fine red colour and the female green, though differently marked from the female of _E. galeritus_. _E. leyboldi_ (of Mas-a-fuera) has the male also red and the female green, but the female is more like that of _E. galeritus_, than it is like the female of its nearer ally in Juan Fernandez. Mr. Sclater supposes, that the ancient parent form of these three birds had the sexes alike, as in the present Chilian bird; that a pair (or a female having fertilised ova) reached Juan Fernandez and colonised it. Under the action of sexual selection (unchecked by some conditions which had impaired its efficacy on the continent) the male gradually assumed a brilliant plumage, and the female also slightly changed its markings. Before this change was completed the bird had established an isolated colony on Mas-a-fuera; and here the process of change was continued in the male, but from some unknown cause checked in the female, which thus remains nearer the parent form. Lastly the slightly modified Chilian bird again reached Juan Fernandez and exists there side by side with its strangely altered cousin.

All the phenomena can thus be accounted for by known laws, on the theory of very rare accidental immigrations from the {51}mainland. The species are here so very few, that the greatest advocate for continental extensions would hardly call such vast causes into action, to account for the presence of these three birds on so small and so remote an island, especially as the union must have continued down to the time of existing species. But if accidental immigration has sufficed here, it will also assuredly have sufficed where the islands are larger, and the chances of reaching them proportionately greater; and it is because an important principle is here illustrated on so small a scale, and in so simple a manner as to be almost undeniable, that we have devoted a paragraph to its elucidation.

A few Coleoptera from Juan Fernandez present analogous phenomena. All belong to Chilian genera, while a portion of them constitute peculiar species.

Land-shells are rather plentiful, there being about twenty species belonging to seven genera, all found in the adjacent parts of South America; but all the species are peculiar, as well as four others found on the island of Mas-a-fuera.

_III. Tropical North America, or the Mexican Sub-region._

This sub-region is of comparatively small extent, consisting of the irregular neck of land, about 1,800 miles long, which connects the North and South American continents. Almost the whole of its area is mountainous, being in fact a continuation of the great range of the Rocky Mountains. In Mexico it forms an extensive table-land, from 6,000 to 9,000 feet above the sea, with numerous volcanic peaks from 12,000 to 18,000 feet high; but in Yucatan and Honduras, the country is less elevated, though still mountainous. On the shores of the Caribbean Sea and Gulf of Mexico, there is a margin of low land from 50 to 100 miles wide, beyond which the mountains rise abruptly; but on the Pacific side this is almost entirely wanting, the mountains rising almost immediately from the sea shore. With the exception of the elevated plateaus of Mexico and Guatemala, and the extremity of the peninsula of Yucatan, the whole of Central America is clothed with forests; and as its surface is much broken up into hill and valley, and the volcanic {52}soil of a large portion of it is very fertile, it is altogether well adapted to support a varied fauna, as it does a most luxuriant vegetation. Although many peculiar Neotropical types are absent, it yet possesses an ample supply of generic and specific forms; and, as far as concerns birds and insects, is not perhaps inferior to the richest portions of South America in the number of species to be found in equal areas.

Owing to the fact that the former Republic of Mexico comprised much territory that belongs to the Nearctic region, and that many Nearctic groups extend along the high-lands to the capital city of Mexico itself, and even considerably further south, there is much difficulty in determining what animals really belong to this sub-region. On the low-lands, tropical forms predominate as far as 28° N. latitude; while on the cordilleras, temperate forms prevail down to 20°, and are found even much farther within the tropics.

_Mammalia._--Very few peculiar forms of Mammalia are restricted to tropical North America; which is not to be wondered at when we consider the small extent of the country, and the facility of communication with adjacent sub-regions. A peculiar form of tapir (_Elasmognathus bairdi_) inhabits Central America, from Panama to Guatemala, and, with _Myxomys_, a genus of Muridæ, are all at present discovered. _Bassaris_, a remarkable form of Procyonidæ, has been included in the Nearctic region, but it extends to the high-lands of Guatemala. _Heteromys_, a peculiar genus of Saccomyidæ or pouched rats, inhabits Mexico, Honduras, Costa Rica, and Trinidad. Five genera of monkeys extend here,--_Ateles_, _Mycetes_, _Cebus_, _Nyctipithecus_, and _Saimiris_; the two former alone reaching Mexico, the last only going as far as Costa Rica. Other typical Neotropical forms are _Galera_, the tayra, belonging to the weasel family; _Nasua_, the coatimundi; _Dicotyles_, the peccary; _Cercolabes_, the tree porcupine; _Dasyprocta_, the agouti; _Cælogenys_, the paca; _Choloepus_, and _Arctopithecus_, sloths; _Cyclothurus_, an ant-eater; _Tatusia_, an armadillo; and _Didelphys_, oppossum. Of Northern forms, _Sorex_, _Vulpes_, _Lepus_, and _Pteromys_ reach Guatemala.

_Birds._--The productiveness of this district in bird life, may {53}be estimated from the fact, that Messrs. Salvin and Sclater have catalogued more than 600 species from the comparatively small territory of Guatemala, or the portion of Central America between Mexico and Honduras. The great mass of the birds of this sub-region are of Neotropical families and genera, but these are intermingled with a number of migrants from temperate North America, which pass the winter here; with some northern forms on the high-lands; and with a considerable number of peculiar genera, mostly of Neotropical affinities.