PART III. (_continued._)

_ZOOLOGICAL GEOGRAPHY:_

_A REVIEW OF THE CHIEF FORMS OF ANIMAL LIFE IN THE SEVERAL REGIONS AND SUB-REGIONS, WITH THE INDICATIONS THEY AFFORD OF GEOGRAPHICAL MUTATIONS._

{3}CHAPTER XIV.

THE NEOTROPICAL REGION.

This region, comprehending not only South America but Tropical North America and the Antilles, may be compared as to extent with the Ethiopian region; but it is distinguished from all the other great zoological divisions of the globe, by the small proportion of its surface occupied by deserts, by the large proportion of its lowlands, and by the altogether unequalled extent and luxuriance of its tropical forests. It further possesses a grand mountain range, rivalling the Himalayas in altitude and far surpassing them in extent, and which, being wholly situated within the region and running through eighty degrees of latitude, offers a variety of conditions and an extent of mountain slopes, of lofty plateaus and of deep valleys, which no other tropical region can approach. It has a further advantage in a southward prolongation far into the temperate zone, equivalent to a still greater extension of its lofty plateaus; and this has, no doubt, aided the development of the peculiar alpine forms of life which abound in the southern Andes. The climate of this region is exceptionally favourable. Owing to the lofty mountain range situated along its western margin, the moisture-laden trade winds from the Atlantic have free access to the interior. A sufficient proportion of this moisture reaches the higher slopes of the Andes, where its condensation gives rise to innumerable streams, which cut deep ravines and carry down such an amount of sediment, that they have formed the vast plains of the Amazon, of {4}Paraguay, and of the Orinooko out of what were once, no doubt, arms of the sea, separating the large islands of Guiana, Brazil, and the Andes. From these concurrent favourable conditions, there has resulted that inexhaustible variety of generic and specific forms with a somewhat limited range of family and ordinal types, which characterise neotropical zoology to a degree nowhere else to be met with.

Together with this variety and richness, there is a remarkable uniformity of animal life over all the tropical continental portions of the region, so that its division into sub-regions is a matter of some difficulty. There is, however, no doubt about separating the West Indian islands as forming a well-marked subdivision; characterised, not only by that poverty of forms which is a general feature of ancient insular groups, but also by a number of peculiar generic types, some of which are quite foreign to the remainder of the region. We must exclude, however, the islands of Trinidad, Tobago, and a few other small islands near the coast, which zoologically form a part of the main land. Again, the South Temperate portion of the continent, together with the high plateaus of the Andes to near the equator, form a well-marked subdivision, characterised by a peculiar fauna, very distinct both positively and negatively from that of the tropical lowland districts. The rest of Tropical South America is so homogeneous in its forms of life that it cannot be conveniently subdivided for the purposes of a work like the present. There are, no doubt, considerable differences in various parts of its vast area, due partly to its having been once separated into three or more islands, in part to existing diversities of physical conditions; and more exact knowledge may enable us to form several provinces or perhaps additional sub-regions. A large proportion of the genera, however, when sufficiently numerous in species, range over almost the whole extent of this sub-region wherever the conditions are favourable. Even the Andes do not seem to form such a barrier as has been supposed. North of the equator, where its western slopes are moist and forest-clad, most of the genera are found on both sides. To the south of this line its western valleys are arid and its lower plains almost deserts; and thus the absence of a {5}number of groups to which verdant forests are essential, can be traced to the unsuitable conditions rather than to the existence of the mountain barrier. All Tropical South America, therefore, is here considered to form but one sub-region.

The portion of North America that lies within the tropics, closely resembles the last sub-region in general zoological features. It possesses hardly any positive distinctions; but there are several of a negative character, many important groups being wholly confined to South America. On the other hand many genera range into Mexico and Guatemala from the north, which never reach South America; so that it is convenient to separate this district as a sub-region, which forms, to some extent, a transition to the Nearctic region.

_General Zoological Features of the Neotropical Region._--Richness combined with isolation is the predominant feature of Neotropical zoology, and no other region can approach it in the number of its peculiar family and generic types. It has eight families of Mammalia absolutely confined to it, besides several others which are rare elsewhere. These consist of two families of monkeys, Cebidæ and Hapalidæ, both abounding in genera and species; the Phyllostomidæ, or blood-sucking bats; Chinchillidæ and Caviidæ among rodents; besides the greater part of the Octodontidæ, Echimyidæ and Cercolabidæ. Among edentata, it has Bradypodidæ, or sloths, Dasypodidæ, or armadillos, and Myrmecophagidæ, or anteaters, constituting nearly the entire order; while Procyonidæ, belonging to the carnivora, and Didelphyidæ, a family of marsupials, only extend into the Nearctic region. It has also many peculiar groups of carnivora and of Muridæ, making a total of full a hundred genera confined to the region. Hardly less remarkable is the absence of many wide-spread groups. With the exception of one genus in the West Indian islands and a _Sorex_ which reaches Guatemala and Costa Rica, the Insectivora are wholly wanting; as is also the extensive and wide-spread family of the Viverridæ. It has no oxen or sheep, and indeed no form of ruminant except deer and llamas; neither do its vast forests and grassy plains support a single form of non-ruminant ungulate, except the tapir and the peccary.

{6}_Birds._--In birds, the Neotropical region is even richer and more isolated. It possesses no less than 23 families wholly confined within its limits, with 7 others which only extend into the Nearctic region. The names of the peculiar families are: Cærebidæ, or sugar-birds; Phytotomidæ, or plant-cutters; Pipridæ, or manakins; Cotingidæ, or chatterers; Formicariidæ, or ant-thrushes; Dendrocolaptidæ, or tree-creepers; Pteroptochidæ; Rhamphastidæ, or toucans; Bucconidæ, or puff-birds; Galbulidæ, or jacamas; Todidæ, or todies; Momotidæ, or motmots; Steatornithidæ, the guacharo, or oil-bird; Cracidæ, or curassows; Tinamidæ, or tinamous; Opisthocomidæ, the hoazin; Thinocoridæ; Cariamidæ; Aramidæ; Psophiidæ, or trumpeters; Eurypygidæ, or sun-bitterns; and Palamedeidæ, or horned-screamers. The seven which it possesses in common with North America are: Vireonidæ, or greenlets; Mniotiltidæ, or wood-warblers; Tanagridæ, or tanagers; Icteridæ, or hang-nests; Tyrannidæ, or tyrant-shrikes; Trochilidæ, or humming-birds; and Conuridæ, or macaws. Most of these families abound in genera and species, and many are of immense extent; such as Trochilidæ, with 115 genera, and nearly 400 species; Tyrannidæ, with more than 60 genera and nearly 300 species; Tanagridæ, with 43 genera and 300 species; Dendrocolaptidæ with 43 genera and more than 200 species; and many other very large groups. There are nearly 600 genera peculiar to the Neotropical region; but in using this number as a basis of comparison with other regions we must remember, that owing to several ornithologists having made the birds of South America a special study, they have perhaps been more minutely subdivided than in the case of other entire tropical regions.

_Distinctive Characters of Neotropical Mammalia._--It is important also to consider the kind and amount of difference between the various animal forms of this region and of the Old World. To begin with the Quadrumana, all the larger American monkeys (Cebidæ) differ from every Old World group in the possession of an additional molar tooth in each jaw; and it is in this group alone that the tail is developed into a prehensile organ of wonderful power, adapting the animals to a purely arboreal life. Four of the genera, comprising more than half the {7}species, have the prehensile tail, the remainder having this organ either short, or lax as in the Old World monkeys. Other differences from Old World apes, are the possession of a broad nasal septum, and a less opposable thumb; and the absence of cheek-pouches, ischial callosities, and a bony ear-tube. The Hapalidæ, or marmozets, agree with the Cebidæ in all these characters, but have others in addition which still more widely separate them from the Simiidæ; such as an additional premolar tooth, acute claws, and thumb not at all opposable; so that the whole group of American monkeys are radically different from the remainder of the order.

The Procyonidæ are a distinct family of Carnivora, which make up for the scarcity of Mustelidæ in South America. The Suidæ are represented by the very distinct genus _Dicotyles_ (Peccary) forming a separate sub-family, and differing from all other genera in their dentition, the absence of tail and of one of the toes of the hind feet, the possession of a dorsal gland, and only two mammæ. The rodents are represented by the Chinchillidæ and Caviidæ, the latter comprising the largest animals in the order. The Edentata are almost wholly confined to this region; and the three families of the sloths (Bradypodidæ), armadillos (Dasypodidæ), and ant-eaters (Myrmecophagidæ), are widely separated in structure from any Old World animals. Lastly, we have the opossums (Didelphyidæ), a family of marsupials, but having no close affinity to any of the numerous Australian forms of that order. We have already arrived at the conclusion that the presence of marsupials in South America is not due to any direct transference from Australia, but that their introduction is comparatively recent, and that they came from the Old World by way of North America (vol. i., p. 155). But the numerous and deep-seated peculiarities of many other of its mammalia, would indicate a very remote origin; and a long-continued isolation of South America from the rest of the world is required, in order to account for the preservation and development of so many distinct groups of comparatively low-type quadrupeds.

_Distinctive Characters of Neotropical Birds._--The birds which are especially characteristic of this region, present similar distinctive features. In the enormous group of Passerine {8}birds which, though comprising nearly three-fourths of the entire class, yet presents hardly any well-marked differences of structure by which it can be subdivided--the families confined to America are, for the most part, more closely related to each other than to the Old World groups. The ten families forming the group of "Formicaroid Passeres," in our arrangement (vol. i., p. 94), are characterised by the absence of singing muscles in the larynx, and also by an unusual development of the first primary quill; and seven of this series of families (which are considered to be less perfectly developed than the great mass of Old World passeres) are exclusively American, the three belonging to the Eastern hemisphere being of small extent. Another group of ten families--our "Tanagroid Passeres," are characterised by the abortion or very rudimentary condition of the first quill; and of these, five are exclusively American, and have numerous genera and species, while only two are non-American, and these are of small extent. On the other hand the "Turdoid Passeres," consisting of 23 families and comprising all the true "singing-birds," is poorly represented in America; no family being exclusively Neotropical, and only three being at all fully represented in South America, though they comprise the great mass of the Old World passeres. These peculiarities, which group together whole series of families of American birds, point to early separation and long isolation, no less surely than the more remarkable structural divergences presented by the Neotropical mammalia.

In the Picariæ, we have first, the toucans (Rhamphastidæ); an extraordinary and beautiful family, whose enormous gaily-coloured bills and long feathered tongues, separate them widely from all other birds. The Galbulidæ or jacamars, the motmots (Momotidæ), and the curious little todies (Todidæ) of the Antilles, are also isolated groups. But most remarkable of all is the wonderful family of the humming-birds, which ranges over all America from Tierra del Fuego to Sitka, and from the level plains of the Amazon to above the snow-line on the Andes; which abounds both in genera, species, and individuals, and is yet strictly confined to this continent alone! How vast must have been the time required to develop those beautiful and {9}highly specialized forms out of some ancestral swift-like type; how complete and long continued the isolation of their birthplace to have allowed of their modification and adaptation to such divergent climates and conditions, yet never to have permitted them to establish themselves in the other continents. No naturalist can study in detail this single family of birds, without being profoundly impressed with the vast antiquity of the South American continent, its long isolation from the rest of the land surface of the globe, and the persistence through countless ages of all the conditions requisite for the development and increase of varied forms of animal life.

Passing on to the parrot tribe, we find the peculiar family of the Conuridæ, of which the macaws are the highest development, very largely represented. It is in the gallinaceous birds however that we again meet with wholly isolated groups. The Cracidæ, including the curassows and guans, have no immediate relations with any of the Old World families. Professor Huxley considers them to approach nearest to (though still very remote from) the Australian megapodes; and here, as in the case of the marsupials, we probably have divergent modifications of an ancient type once widely distributed, not a direct communication between the southern continents. The Tinamidæ or tinamous, point to a still more remote antiquity, since their nearest allies are believed to be the Struthiones or ostrich tribe, of which a few representatives are scattered widely over the globe. The hoazin of Guiana (Opisthocomus) is another isolated form, not only the type of a family, but perhaps of an extinct order of birds. Passing on to the waders, we have a number of peculiar family types, all indicative of antiquity and isolation. The _Cariama_ of the plains of Brazil, a bird somewhat intermediate between a bustard and a hawk, is one of these; the elegant _Psophia_ or trumpeter of the Amazonian forests; the beautiful little sun-bittern of the river banks (_Eurypyga_); and the horned screamers (_Palamedea_), all form distinct and isolated families of birds, to which the Old World offers nothing directly comparable.

_Reptiles._--The Neotropical region is very rich in varied forms of reptile life, and the species are very abundant. It has six {10}altogether peculiar families, and several others which only range into the Nearctic region, as well as a very large number of peculiar or characteristic genera. As the orders of reptiles differ considerably in their distributional features, they must be considered separately.

The snakes (Ophidia) differ from all other reptiles, and from most other orders of vertebrates, in the wide average distribution of the families; so that such an isolated region as the Neotropical possesses no peculiar family, nor even one confined to the American continent. The families of most restricted range are--the Scytalidæ, only found elsewhere in the Philippine islands; the Amblycephalidæ, common to the Oriental and Neotropical regions; and the Tortricidæ, most abundant in the Oriental region, but found also in the Austro-Malay islands and Tropical South America. Sixteen of the families of snakes occur in the region, the Colubridæ, Amblycephalidæ, and Pythonidæ, being those which are best represented by peculiar forms. There are 25 peculiar or characteristic genera, the most important being _Dromicus_ (Colubridæ); _Boa_, _Epicrates_, and _Ungalia_ (Pythonidæ); _Elaps_ (Elapidæ); and _Craspedocephalus_ (Crotalidæ).

The lizards (Lacertilia) are generally more restricted in their range; hence we find that out of 15 families which inhabit the region, 5 are altogether peculiar, and 4 more extend only to N. America. The peculiar families are Helodermidæ, Anadiadæ, Chirocolidæ, Iphisiadæ, and Cercosauridæ; but it must be noted that these all possess but a single genus each, and only two of them (Chirocolidæ and Cercosauridæ) have more than a single species. The families which range over both South and North America are Chirotidæ, Chalcidæ, Teidæ, and Iguanidæ; the first and second are of small extent, but the other two are very large groups, the Teidæ possessing 12 genera and near 80 species; the Iguanidæ 40 genera and near 150 species; the greater part of which are Neotropical. There are more than 50 peculiar or highly characteristic genera of lizards, about 40 of which belong to the Teidæ and Iguanidæ, which thus especially characterize the region. The most important and characteristic genera are the following; _Ameiva_ (Teidæ); _Gymnopthalmus_ (Gymnopthalmidæ); {11}_Celestus_ and _Diploglossus_ (Scincidæ); _Sphærodactylus_ (Geckotidæ); _Liocephalus_, _Liolæmus_, _Proctotretus_, and many smaller genera (Iguanidæ). The three extensive Old World families Varanidæ, Lacertidæ, and Agamidæ, are absent from the entire American continent.

In the order Crocodilia, America has the peculiar family of the alligators (Alligatoridæ), as well as several species of true crocodiles (Crocodilidæ). The Chelonia (tortoises) are represented by the families Testudinidæ and Chelydidæ, both of wide range; but there are six peculiar genera,--_Dermatemys_ and _Staurotypus_ belonging to the former family,--_Peltocephalus_, _Podocnemis_, _Hydromedusa_, and _Chelys_, to the latter. Some of the Amazon river-turtles of the genus _Podocnemys_ rival in size the largest species of true marine turtles (Cheloniidæ), and are equally good for food.

_Amphibia._--The Neotropical region possesses representatives of sixteen families of Amphibia of which four are peculiar; all belonging to Anoura or tail-less Batrachians. The Cæciliadæ or snake-like amphibia, are represented by two peculiar genera, _Siphonopsis_ and _Rhinatrema_. Tailed Batrachians are almost unknown, only a few species of _Spelerpes_ (Salamandridæ) entering Central America, and one extending as far south as the Andes of Bogota in South America. Tail-less Batrachians on the other hand, are abundant; there being 14 families represented, of which 4,--Rhinophryndæ, Hylaplesidæ, Plectromantidæ, and Pipidæ are peculiar. None of these families contain more than a single genus, and only the second more than a single species; so that it is not these which give a character to the South American Amphibia-fauna. The most important and best represented families are, Ranidæ (true frogs), with eleven genera and more than 50 species; Polypedatidæ (tree-frogs) with seven genera and about 40 species; Hylidæ (tree-frogs) with eight genera and nearly 30 species; Engystomidæ (toads) (5 genera), Bombinatoridæ (frogs), (4 genera), Phryniscidæ and Bufonidæ (toads), (each with 2 genera), are also fairly represented. All these families are widely distributed, but the Neotropical genera are, in almost every case, peculiar.

{12}_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 and _Percichthys_ South 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 being _Acara_ (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 which _Pimelodus_ (42 sp.), and _Platystoma_ (11 sp.), are the most important; the Siluridæ stenobranchiæ by 11 genera, the chief being _Doras_ (13 sp.), _Auchenipterus_ (9 sp.), and _Oxydoras_ (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.) and _Callichthys_ (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 being _Haplochiton_. The Cyprinodontidæ are represented by 18 genera, the most important being, _Pæcilia_ (16 sp.), _Girardinus_ (10 sp.), and _Gambusia_ (8 sp.) The Osteoglossidæ, found in Australian and African rivers, are represented in South America by the peculiar _Arapaima_, the "pirarucu" of the {13}Amazon. The ancient Sirenoidei, also found in Australia and Africa, have the _Lepidosiren_ as their American representative. Lastly, _Ellipisurus_ is 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 of 4/5; while of 683 genera of land-birds no less than 576 are peculiar, being almost exactly 5/6 of 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 Nearctic {14}region; 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_, _Ceratina_ and _Dircenna_ are 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 genus _Hætera_ and its allies, whose transparent wings are delicately marked with patches of orange, pink, or violet. The genus _Morpho_ is 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 genera _Catagramma_ and _Callithea_, whose exquisite colours and symmetrical markings are unique and indescribable; and these are in some cases rivalled by _Agrias_ and _Prepona_, 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 genus _Thecla_ is wonderfully developed, and the South {15}American 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 are _Oxychila_ (11 sp.), _Hiresia_ (14 sp.), and _Ctenostoma_ (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 genus _Peridexia_ is divided between Brazil and Madagascar,--a somewhat similar distribution to that of _Urania_ noticed 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. The {16}most important of these are _Agra_ (150 sp.), _Ardistonus_ (44 sp.), _Schizogenius_ (25 sp.), _Pelecium_ (24 sp.), _Calophena_ (22 sp.), _Aspidoglossa_ (21 sp.), and _Lia_, _Camptodonotus_, _Stenocrepis_, and _Lachnophorus_, 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 are _Antarctia_ (29 sp,), all except two or three confined to South Temperate America; _Scelodontis_ (10 sp.), mostly Chilian; _Feronomorpha_ (6 sp.) all Chilian; and _Tropidopterus_ (4 sp.), all Chilian. _Helluomorpha_ (18 sp.), is confined to North and South America; _Galerita_, _Callida_, and _Tetragonoderus_, are large genera which are chiefly South American but with a few species scattered over the other tropical regions, _Casnonia_ and _Lebia_ are cosmopolite, but most abundant in South America. _Pachyteles_ is mostly South American but with a few species in West Africa; while _Lobodonotus_ has 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 are _Syndesus_, confined to Tropical South America and Australia, and _Platycerus_ which is Palæarctic and Nearctic, with one species in Brazil. The most remarkable genus is undoubtedly _Chiasognathus_, confined to Chili. These are large insects of metallic green colours, and armed with enormous serrated mandibles. The allied genera, _Pholidotus_ and _Sphenognathus_, inhabit Tropical South America. _Streptocerus_ confined to Chili, is interesting, as being allied to the Australian _Lamprima_. The other genera present no remarkable features; but _Sclerognathus_ and _Leptinoptera_ are 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 is _Gymnetis_, which, with its allies _Cotinis_ and _Allorhina_, 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; {17}and _Trigonopeltastes_ (6 sp.), allied to the European _Trichius_. The non-peculiar genera are, _Stethodesma_, of which half the species are African and half tropical American; and _Euphoria_, 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 are _Conognatha_ and _Halecia_, which have a wide range over most parts of the region; and _Dactylozodes_, confined to the south temperate zone. Of important genera which range beyond the region, _Dicerca_ is mainly Nearctic and Palæarctic; _Cinyra_ has a species in North America and one in Australia; _Curis_ is divided between Chili and Australia; the Australian genus _Stigmodera_ has a species in Chili; _Polycesta_ has a species in Madagascar, two in the Mediterranean region, and a few in North America; _Acherusia_ is divided between Australia and Brazil; _Ptosima_ has one species in south temperate America, the rest widely scattered from North America to the Philippines; _Actenodes_ has a single species in North America and another in West Africa; _Colobogaster_ has 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, _Parandra_ and _Mallodon_, which are widely distributed; and _Ergates_, found also in California and Europe. The most remarkable genera are, the magnificently-coloured _Psalidognathus_ and _Pyrodes_; the large and strangely marked {18}_Macrodontia_; and _Titanus_, 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 elegant _Ibidion_ (80 sp.); the richly-coloured _Chrysoprasis_ (47 sp.); the prettily-marked _Trachyderes_ (53 sp.); with _Odontocera_ (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, _Oeme_ and _Cyrtomerus_, which have each a species in West Africa, and _Hammatocerus_, 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 are _Hemilophus_ (80 sp.), _Colobothea_ (70 sp.), _Acanthoderes_ (56 sp.), _Oncoderes_ (48 sp.), _Lepturgus_ (40 sp.), _Hypsioma_ (32 sp.), and _Tæniotes_ (20 sp.). _Macropus longimanus_, commonly called the harlequin beetle, is one of the largest and most singularly-marked insects in the whole family. _Leptostylus_ has a single species in New Zealand; _Acanthoderes_ has one species in Europe, W. Africa, and Australia, respectively; _Spalacopsis_ has a species in W. Africa; _Pachypeza_ is common to S. America and the Philippines; _Mesosa_ is Oriental and Palæarctic, but has one species on the Amazon; _Apomecyna_ ranges through the tropics of the Eastern Hemisphere, but has two species in S. America; _Acanthocinus_ has one species in Tasmania, and the rest in South America, North America, and Europe; _Phæa_ is 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 scattered {19}over 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 of _generic_ forms has been here brought about, without any important deviation from the great _family_ types 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:

West India Islands. American Continent.

Operculata Gen. 22 Sp. 608 14 151 Inoperculata " 18 " 737 22 1251

The extensive family of the Helicidæ is represented by 22 genera, of which 6 are peculiar. _Spiraxis_ is confined to Central America and the Antilles; _Stenopus_ and _Sagda_ are Antillean only; _Orthalicus_, _Macroceramus_, and _Bulimulus_ have a wider range, the last two extending into the southern United {20}States. 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; and _Streptaxis_, 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 genera _Cistula_ and _Chondropoma_ are the most important, ranging over all the tropical parts of the region. Other important genera are _Cyclotus_ and _Megalomastoma_; while _Cyclophorus_ also 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, with _Trochatella_ and _Alcadia_, is confined to the Antilles, while the wide-spread _Helicina_ is 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 of {21}South 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, {22}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.

{23}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; as _Lagothrix_, _Pithecia_, and _Brachyurus_, limited to the great Amazonian forests; _Eriodes_ to south-east Brazil; and _Callithrix_ to 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 genus _Tapirus_ (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 (_Hydrochoerus_) the largest known rodent, belonging to the Caviidæ; the larger ant-eaters (_Myrmecophaga_); sloths of the genus _Bradypus_; 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, _Aulacodes_ and _Petromys_, 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 best {24}developed. 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 the _Tillandsia 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 (_Cebus_ sp.); 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), Coerebidæ (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, _Psophia_ and _Eurypyga_ types 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.

{25}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 spread {26}into the Amazonian valley. Guiana still boasts such remarkable forms as the cardinal chatterer (_Phoenicocercus_), the military chatterer (_Hæmatoderus_), as well as _Querula_, _Gymnoderus_, and _Gymnocephalus_; 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 has _Ptilochloris_, _Casiornis_, _Tijuca_, _Phibalura_, and _Calyptura_; while not a single genus of this family, except perhaps _Heliochæra_, 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) and _Pteronura_ (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 geological {27}antiquity) 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, {28}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.

{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.

The genera of birds peculiar to this sub-region belong to the following families:--Turdidæ (2 genera); Troglodytidæ (1 gen.); Vireonidæ (1 gen.); Corvidæ (2 gen.); Ampelidæ (1 gen.); Tanagridæ (1 gen.); Fringillidæ (2 gen.); Icteridæ (1 gen.); Formicariidæ (2 gen.); Tyrannidæ (2 gen.); Cotingidæ (1 gen.); Momotidæ (1 gen.); Trogonidæ (1 gen.); Trochilidæ (14 gen.); Conuridæ (1 gen.); Cracidæ (2 gen.); Strigidæ (1 gen.); in all 37 genera of land-birds. The Neotropical families that do not extend into this sub-region are, Pteroptochidæ; the sub-family _Furnariinæ_ of the Dendrocolaptidæ; the sub-family _Conophaginæ_ of the Tyrannidæ; the sub-family _Rupicolinæ_ of the Cotingidæ; Phytotomidæ; Todidæ; Opisthocomidæ; Chionididæ; Thinocoridæ; Cariamidæ; Psophiidæ; Eurypygidæ; Palamedeidæ; and Struthionidæ. On the other hand Paridæ, Certhiidæ, Ampelidæ, and Phasianidæ, are northern families represented here, but which do not reach South America; and there are also several northern genera and species, of Turdidæ, Troglodytidæ, Mniotiltidæ, Vireonidæ, Fringillidæ, Corvidæ, Tetraonidæ, and Strigidæ, which are similarly restricted. Some of the most remarkable of the Neotropical genera only extend as far as Costa Rica and Veragua,--countries which possess a rich and remarkable fauna. Here only are found an umbrella bird, (_Cephalopterus glabricollis_); a bell bird (_Chasmorhynchus tricarunculatus_); and species of _Dacnis_ (Ceroebidæ), _Buthraupis_, _Eucometis_, _Tachyphonus_ (Tanagridæ), _Xiphorhynchus_ (Dendrocolaptidæ); _Hypocnemis_ (Formicariidæ); _Euscarthmus_ (Tyrannidæ); _Attila_ (Cotingidæ); _Piprites_ (Pipridæ); _Capito_, _Tetragonops_ (Megalæmidæ); _Selenidera_ (Rhamphastidæ); _Neomorphus_ {54}(Cuculidæ); _Monasa_ (Bucconidæ); many genera of Trochilidæ; and _Nothocercus_ (Tinamidæ); none of which extend further north. A considerable number of the peculiar genera noted above, are also found in this restricted area, which is probably one of the richest ornithological districts on the globe.

_Reptiles._--These are much less known than the preceding classes, but they afford several peculiar and interesting forms. Snakes are perhaps the least remarkable; yet there are recorded 4 peculiar genera of Calamariidæ, 1 of Colubridæ, 1 of Homalopsidæ, 3 of Dipsadidæ; while _Boa_ and _Elaps_ are in common with South America. Lizards are much more specially developed. _Chirotes_, one of the Amphisbænians, is confined to Mexico and the southern part of the Nearctic region; _Heloderma_ forming a peculiar family, Helodermidæ, is Mexican only; _Abronia_ and _Barissia_ (Zonuridæ) are also Mexican, as is _Siderolampus_ belonging to the Scincidæ, while _Blepharactitis_ (same family) inhabits Nicaragua; _Brachydactylus_, one of the geckoes, is from Costa Rica; while _Phymatolepis_, _Lamanctus_, _Corytheolus_, _Cachrix_, _Corythophanes_ and _Chamæleopsis_, all belonging to the Iguanidæ, are confined to various parts of the sub-region. In the same family we have also the Antillean, _Cyclura_, and the Nearctic _Phrynosoma_ and _Tropidolepis_, as well as the wide-spread American genus _Anolius_.

Among the tortoises, _Staurotypus_, allied to _Chelydra_, is found in Mexico and Guatemala; and another genus, _Claudius_, has been lately described from Mexico.

_Amphibia._--These are chiefly Batrachians; _Rhinophryna_ (forming a peculiar family) being confined to Mexico; _Triprion_, a genus of Hylidæ, inhabiting Yucatan, with _Leyla_ and _Strabomantis_ (Polypedatidæ) found only in Costa Rica and Veragua, are peculiar genera. The Salamandridæ, so abundant in the Nearctic region, are represented by a few species of _Amblystoma_ and _Spelerpes_.

_Fresh-water fish._--Since the British Museum catalogue was published, a valuable paper by Dr. Günther, in the Transactions of the Zoological Society for 1868, furnishes much additional information on the fishes of Central America. In that part of the region south of Mexico, 106 species of fresh-water fishes are {55}enumerated; and 17 of these are found in streams flowing into both the Atlantic and Pacific Oceans. On the whole, 11 families are represented among the fresh-water fish, and about 38 genera. Of these, 14 are specially Nearctic,--_Amiurus_ (Siluridæ); _Fundulus_ (Cyprinodontidæ); _Sclerognathus_ (Cyprinidæ); and _Lepidosteus_ (Ganoidei). A much larger number are Neotropical; and several Neotropical genera, as _Heros_ and _Poecilia_, are more largely developed here than in any other part of the region. There are also a considerable number of peculiar genera;--_Petenia_, _Theraps_, and _Neotrophus_ (Chromides); _Ælurichthys_ (Siluridæ); _Chalcinopsis_ (Characniidæ); _Characodon_, _Belonesox_, _Pseudoxiphophorus_, _Platypoecilus_, _Mollienesia_, and _Xiphophorus_ (Cyprinodontidæ). A few peculiar Antillean forms are also present; as _Agonostoma_ (Mugilidæ); _Gambusia_ and _Girardinuus_ (Cyprinodontidæ). The other families represented are Percidæ (1 genus); Pristopomatidæ (2 gen.); Gobiidæ (1 gen.); Clupeidæ (2 gen.); and Gymnotidæ (1 genus).

On the whole the fish-fauna is typically Neotropical, but with a small infusion of Nearctic forms. There are a considerable proportion of peculiar genera, and almost all the species are distinct from those of other countries. The predominant family is that of the Cyprinodontidæ, represented by 12 genera; and the genus _Heros_ (Chromidæ) has here its maximum development, containing between thirty and forty species. Dr. Günther considers that a number of sub-faunas can be distinguished, corresponding to some extent, with the islands into which the country would be divided by a subsidence of about 2,000 feet. The most important of these divisions is that separating Honduras from Costa Rica, and as it also divides a very marked ornithological fauna we have every reason to believe that such a division must have existed during the latter portion of the tertiary epoch. We shall find some farther evidence of this division in the next class.

_Insects._--The butterflies of various parts of Central America and Mexico, having been largely collected, offer us some valuable evidence as to the relations of this sub-region. Their general character is wholly Neotropical, about one half of the {56}South American genera being found here. There are also a few peculiar genera, as, _Drucina_ (Satyridæ); _Microtia_ (Nymphalidæ); _Eumæus_ (Lycænidæ); and _Eucheira_ (Pieridæ). _Clothilda_ (Nymphalidæ) is confined to this sub-region and the Antilles. The majority of the genera range over the whole sub-region from Panama to Mexico, but there are a considerable number, comprising many of the most characteristic South American forms, which do not pass north of Costa Rica or Nicaragua. Such are _Lycorea_, _Ituna_, _Thyridia_, _Callithomia_, _Oleria_ and _Ceratina_,--all characteristic South American groups of Danaidæ; _Pronophila_ and _Dynastor_ (Satyridæ); _Protogonius_, _Pycina_, _Prepona_, _Nica_, _Ectima_ and _Colænis_ (Nymphalidæ); _Eurybia_ and _Methonella_ (Nemeobiidæ); _Hades_, and _Panthemos_ (Erycinidæ).

_Coleoptera._--These present some interesting features, but owing to their vast number only a few of the more important families can be noticed.

Cicindelidæ.--The only specially Neotropical genera recorded as occurring in this sub-region, are _Ctenostoma_ and _Hiresia_, both reaching Mexico.

Carabidæ.--Several genera are peculiar. _Molobrus_ is found in all parts of the sub-region, while _Onychopterygia_, _Phymatocephalus_, and _Anisotarsus_ are Mexican only. There are about 20 South American genera, most of which extend to Mexico, and include such characteristic Neotropical forms as _Agra_, _Callida_, _Coptodera_, _Pachyteles_, _Ardistomus_, _Aspidoglossa_, _Stenocrepis_, and _Pelecium_.

Lucanidæ.--Of this important family there is, strange to say, not a single species recorded in Gemminger and Harold's catalogue up to 1868! It is almost impossible that they can be really absent; yet their place seems to he, to some extent, supplied by an unusual development of the allied Passalidæ, of which there are five South American and six peculiar genera.

Cetoniidæ.--All the larger South American genera extend to Mexico, which country possesses 3 peculiar forms, _Ischnoscelis_, _Psilocnemis_, and _Dialithus_; while _Trigonopeltastes_ is characteristic, having 4 Mexican, 1 Brazilian, and 1 North American species.

{57}Buprestidæ.--In this family there are no peculiar genera. All the large South American groups are absent, the only important and characteristic genus being _Stenogaster_.

Longicorns.--This important group is largely developed, the country being well adapted to them; and their distribution presents some features of interest.

In the Prionidæ there are 6 peculiar genera, the largest being _Holonotus_ with 3 species; two others, _Derotrachus_ and _Mallaspis_, are characteristic; 3 more are common to South America, and 1 to Cuba. The Cerambycidæ are much more numerous, and there are 24 peculiar genera, the most important being _Sphenothecus_, _Entomosterna_, and _Cyphosterna_; while _Crioprosopus_ and _Metaleptus_ are characteristic of the sub-region, although extending into South America; about 12 Neotropical genera extend to Mexico or Guatemala, while 12 more stop short, as far as yet known, at Nicaragua. Lamiidæ have a very similar distribution; 13 genera are peculiar, the most important being _Monilema_, _Hamatoderus_, and _Carneades_, while _Phæa_ and _Lagochirus_ are characteristic. About sixteen typical Neotropical genera extend to Mexico, and 15 more only reach Nicaragua, among which are such important genera as _Anisopus_, _Lepturgus_, and _Callia_.

The land-shells are not sufficiently known to furnish any corresponding results. They are however mostly of South American genera, and have comparatively little affinity for those of the Antilles.

_Relations of the Mexican sub-region to the North and South American Continents._--The sudden appearance of numerous South American forms of Edentata in temperate North America, in Post-Tertiary times, as narrated in