ANIMAL.] DISTRIBUTION 273 V. Tlie Neotropical Region. This is in some respects the richest zoological region on the globe, yet it has certain resemblances to the Australian region, which is the poorest, and which it follows in natural order. This is owing to both being inhabited mainly by low types of Mammalia and birds, some of which have been preserved from early geological times, the Marsupials being a good example. But there has also been some intermigration between south temperate America and Australia, by means of intermediate islands and floating ice, and this has led to a community of forms in a few groups to which such a mode of trans mission was possible. The Mammalia are as abundant and varied as in any other countries except Africa and tropical Asia ; but the region is characterized by poverty in the more highly organized forms, with a corresponding abundance of lower types. Monkeys are abundant, but all belong to two peculiar families Cebidce audllapalidce different in struc ture and of a somewhat lower organization than those of the Old World. About half of them have powerfully prehensile tails, a character unknown among the monkeys of the eastern hemisphere. Bats are very numerous, and one extensive family the Phyllostomidce, or vampyre- bats is peculiar. Insectivora are unknown in South America, but one peculiar genus occurs in the larger Antilles, and a few : shrews in Central America. The Carnivora are but moderately numerous, the Civet family being entirely wanting, as are the bears, with the exception of a solitary species in Chili. There is, however, one peculiar family the Procyonidce which extends over North America as well, A marked feature is the excessive scarcity of the great family of the Ungulata, or hoofed animals. There are no wild cattle, sheep, goats, antelopes, horses, or rhinoceroses ; and only a very few species of tapirs, peccaries, llamas, and deer in their place. Coming to the small and feeble Eodents, however, we find a great abundance and variety of forms, including the largest on the globe. Five families are peculiar or nearly so,- the chinchillas and the cavies being the most important, while all the genera, except Sciurus and Lepiis, are peculiar to the American continent. We now come to the Edentata, the most imperfectly organized and the most characteristic of the Neotropical mammals. There are twelve genera belonging to the three families of the sloths (Bradypodidce), the armadillos (Dasypodidce), and the ant- eaters (Myrmecophagidce). Lastly, we have the Marsupial opossums, which range far over temperate North America, but are most abundant in the tropical regions of South America. In birds the Neotropical region is wonderfully rich. It possesses far more distinct genera and species than any other region, and it has 24 entire families peculiar to it, while the region which comes next in speciality and isola tion as regards this order the Australian has only 16. Most of these peculiar families are, however, of a somewhat low grade of organization, and it is these which abound most in genera and species and give a special feature to the ornithology of the country. These peculiarly American families (for some of them range into North America) are the tyrant fly-catchers (Tyrannidce), the manakins (Pipridce), the chatterers (Cotingidce), the plant-cutters (Phytotomidce), the tree-creepers (Dendrocolaptidtz), the ant-thrushes (Formicariidce), and the wren-thrushes (Pteroptochidai). All these have a deficiency in the sing ing-muscles of the throat, and they comprise more than 200 genera. Then, among the Picariai, which are a low though wide-spread order, we have the toucans (Rhamphastidce), the puff-birds (Bucconidce), the jacamars (Galbulidw], the rnotmots (Momotidce), and the humming birds (Trochilidce), comprising 140 genera. The only peculiar families of high organization arc the sugar- birds (Ccerebidce), the greenlets ( Vireonidae), the hang-nests (Icteridce), and the tanagers (Tanagridce), comprising in all 82 genera. The most highly organized groups of birds, and those which are most abundant in the eastern hemisphere, such as crows, starlings, thrushes, warblers, and flycathers, are either scarce or entirely wanting. Finches are numerous, as are parrots. Among game-birds the higher types, as the grouse (Tetraonidce), are scarce ; while the more lowly-organized curassows (Crdcidce) and tinamous (Tinamidce) are much more abundant and more widely distributed over the whole region. Among the wading groups (Grallce), which are decidedly of low organization, there are 6 peculiar and very isolated families, the most remarkable being the Gariamidce, the Psophiidce (trumpeters), the Eurypygidve (sun-bitterns), and the Palamedeidce (horned-screamers). The very low struthious type is represented by the American ostriches (Rkea). Reptiles are also very abundant in the Neotropical region, and there are many peculiar groups. Snakes are represented by peculiar genera only, the families being almost always widely and often universally distributed in warm regions ; lizards are more restricted in their range, and no less than 5 families are peculiar. to the region, while 9 are found only in the American continent. All are of very small extent except two, the Teidce and Iguanidce, which are very numerous, and comprise the most characteristic American lizards. There are also 4 peculiar families of tailless Batrachians, the most popularly known being the Pipidce, which contains the remarkable Surinam toad. Fresh-water fishes are probably more abundant and varied than in any other region. Three entire families and several sub-family groups are peculiar, and the enormous forest-bordered rivers and extensive tracts of annually flooded woodland have led to the development of special groups of fruit-eating fishes, which, as articles of food, are not only unsurpassed but altogether unequalled in any other part of the globe. Fresh-water rays (Trygonidce] and electric eels (Gymnotidce) are also peculiar to Neotropical rivers, and there are an immense variety of Siluridte, Ckaracinidw, and Gyprinodontidce. It is reported that Professor Agassiz obtained more than a thousand species of fishes in the Amazon alone; but, although this may be exaggeration, there is no -doubt that a still greater number exists in that wonderful river and its tributaries. The insects of tropical America are so inexhaustible in their variety, and so wonderful in their beauty, that it is hopeless to attempt to give an adequate idea of them. The butterflies are far more abundant and more gorgeous than in any other region, and their variety may be imagined from the fact that the peculiar genera are nearly equal in number to those of the rest of the world. The beetles, though very abundant, are not so clearly preponderant over those of all other regions. The stag-beetles (Lucanidce) and rose-chafers (Getoniidai) are somewhat poorly de veloped ; but all the other large families are very abundant, and comprise many forms of extreme beauty and interest. Such are the genera Agra among Carabidse, Pyrodes among Longicorns, and Entimus among Curculionidse. Land-shells equally surpass those of all other regions, but this is owing to the exceptional richness of the West Indian islands, the continent of America being by no means extraordinarily rich in this class of animals. Subdivisions of the Neotropical Region. The manner in which this region may be most naturally and conveniently divided for zoological purposes is doubtful. Almost the whole of tropical South America (excluding only the higher Andes south of Chim- borazo and the dry plain to the west) forms a compact area in which all the more characteristic Neotropical animal groups are developed in their highest luxuriance. This, however, falls natu
VII - 35