Page images

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

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 arethe 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, Epicrotes, 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);

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 (Cheloniidae), 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 aś 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.

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 (Percida); 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,-Chotostomus (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, Poecilia (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 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 f; while of 683 genera of land-birds no less than 576 are peculiar, being almost exactly 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

« EelmineJätka »