Page:Encyclopædia Britannica, Ninth Edition, v. 7.djvu/292

274 274 DIST11IBUTION [ANIMAL. rally into three subdivisions, which may be generally indicated as Guiana, Brazil, and the Eastern Andes, each of which is character ized by a great number of peculiar generic types. These three areas are considered by Professor Newton (in his article BIRDS in thiG work) to be sub-regions, each equivalent to the whole of south temperate America, and to the tropical part of North America, which may be termed the Mexican sub-region. But each of these latter may be also divided. South temperate America consists of a western and an eastern division, each with many distinct groups, while the southern parts of Central America differ greatly from the northern ; and all these subdivisions may be considered as provinces of their respective sub-regions. It seems better, therefore, for the purposes of such a general sketch as the present, to consider the tropical parts of South America, as above limited, to be one great sub-region, characterized by possessing a large proportion of the animal forms of the whole region. It will therefore only be neces sary to indicate in what way the other sub-regions differ from this. The Chilian sub-region, or temperate South America as above defined, is well characterized by its exclusive possession of the family of the Chincliillidce (comprising three genera) and the genus AiMhanifi (the llamas and alpacas), the only representatives of the Camelidce in the New World. It also has a peculiar form of bear, several peculiar genera of rodents, and two peculiar forms of arma dillos. Among birds it has the curious plant-cutters (PJujtotomidce), a peculiar family of waders (Thinocoridcc), about 26 peculiar genera of passerine birds 1 of parrots, 2 of pigeons, and 2 of tiuamous. It also possesses the American ostriches (Rhea), and 3 peculiar genera of plovers. The reptiles are usually of tropical genera, but a few are peculiar. Many of the fresh-water fishes are of peculiar genera, but there are some Australian forms, and even one species (Qaluxicts attcnuatua) is common to New Zealand, Tasmania, and Patagonia. Among insects alone ve meet with indications of a decided affinity for forms of the north temperate zone. There are several butterflies allied to JErcbia, an Arctic genus, and others belonging to the northern genera Hipparchia, Argynnis, and Colias. The mass of the butterflies, however, are purely Neotropical. Of the beetles some are Australian, but the majority are allied to Neo tropical forms ; yet among the Carabidce, or carnivorous ground- beetles, there are many truly northern genera, such as Caralnis, Anchomenus, Trechus, &c. , whose presence supports the theory of a migration along the Andes from the northern hemisphere. (See Wallace s Geographical Distribution of Animals, vol. ii. pp. 44- 48.) In tropical North America, or the Mexican sub-region, we find far less peculiarity. The southern portion from Panama to Nica ragua can hardly be separated zoologically from the adjacent parts of South America, while further north the chief difference consists in the absence of many typical Neotropical groups, and the appear ance of a few which more especially characterize the Nearctic region. A peculiar form of tapir (Elasmognathiis] inhabits Central America, with one or two peculiar genera of rodents ; while such northern forms as Sorex, Vulpes, Lepus, and Pteromys range as far south as Guatemala. Birds are more especially characteristic, since the sub-region possesses no less than 37 peculiar genera of land birds ; but many Neotropical groups are absent. The most im portant of these deficiencies are the Pteroptochidce, and the sub families Furnariince, ConopTiagince, aud Rupicolinoe, as well as most of the peculiar groups of waders. In place of these are found tits (Paridce), creepers (Certhiidce), vaxwings (Ampelidce), and turkeys (PJutsianidce) from the north. The fresh-water fishes as well as the insects are almost wholly Neotropical in character, but exhibit a considerable amount of speciality. There remains the West Indian Islands or the Antillean sub- region, which in the amount of isolation and speciality it exhibits is better marked than any other part of the region. The Mam malia are few but very interesting, as is usually the case in islands separated from continents by very deep sea. There are no monkeys, Garni vora, Ungulates, or Edentata, the only orders represented being the Insectivora and the liodentia. The former, which is unknown in South America, is here represented by a peculiar genus, Solcnodon, belonging to a family, Ccnteiidas, only found elsewhere in Madagascar. The Kodents consist of two very peculiar genera Capromys and Plagiodontia belonging to a family which is espe cially South American, with a peculiai mouse, and an agouti (Dasy- procta] in the lesser Antilles. The birds are far more abundant, about 200 resident species being known, besides a large number of migrants from the United States. These belong to 95 genera, of which about one-third are peculiar. The only entirely peculiar family group is that of the todies (Todidee), small and elegant birds whose nearest allies are the South American motmots and jacamars. The reptiles are not very well known, but they seem tolerably numerous, and mostly allied to South American groups ; and the same remark applies to the fresh- water fishes. Insects are not very abundant, and beetles seem especially scarce considering the luxu riant vegetation of most of the islands. In land-shells, however, thi* very reverse is the case, the Antilles being more productive than any other part of the world. The number of species of West .Indian land-shells i.s equal to that of the entire continent of America, while the number of genera is greater. No less than 11 of the genera are peculiar, a very unusual degree of speciality con sidering the extensive range of most of the genfcra of land-mollusca. VI. The Nearctic Region. This comprises all temperate North America : and its peculiar fauna is best represented in the United States, and especially in that portion extend ing from the Mississippi valley to the Atlantic. It is allied both to the Neotropical and the Paltearctic regions, but it also possesses a considerable number of peculiar or charac teristic forms. Among Mammalia it possesses 3 peculiar genera of moles, 2 of weasels, 2 of hollow-horned ruminants Antilocapra (the prong-buck) and Aplocerus, (the moun tain goat or antelope) and a number of Rodents, among which, the most peculiar are the /Saccomyidce or pouched rats. Of those groups which are more-peculiarly Neotropi cal it has skunks (Mephitis), racoons (Procyon), and opossums (Didelphys). The number of Falrearctic groups is greater, the more important being lynxes, wolves, martens, bears, elks, bisons, sheep, flying-squirrels, and marmots. Of birds there are between forty and fifty genera which are peculiar or highly characteristic. Most of them belong to the passerine families, the wood-warblers (Mniotiltidae) and the finches (FringUlidce) being especially rich, in peculiar groups ; and there are also a few among the thrushes, wrens, crows, hang-nests, woodpeckers, grouse, and some other families. Among the larger birds the turkeys (Meleagris), the ruffed grouse (Ciipidonia, &c.), and the crested partridges (Oreortyx, &c.) are the most remarkable. Heptiles seem to be more numerous than in tlie Palsearctic region. About a dozen genera of snakes are peculiar or characteristic, the most remarkable being the well-known rattle-snakes (Crotalus). Among lizards the so-called &quot; glass-snake &quot; (OpJdsaurus) is a peculiar form analogous to our slow-worm ; while the horned-lizards (PTirynosoma] and many other genera of Iguanidse are peculiar. Fresh. -water fishes are exceedingly numerous and highly peculiar, there being no less than five (or, according to recent authors, eight) peculiar families, and a large number of peculiar genera. The perches and their allies (Percidce, IcJitheltdce, Lalracidce, and EtheostomidcK), the carps (Cyprinidce), the suckers (Catostomidce), and the catfish (Siluridce) are the most abundant groups. In insects the Nearctic region is not remarkably rich or very peculiar. Its butterflies, though tolerably abundant, belong for the most part to well-known European groups with a small infusion of Neotropical forms in the -Southern States. The same may be said of its Coleoptera. Land- shells are tolerably plentiful but not strikingly peculiar ; the Alleghany district being the most productive, and possessing a large number of peculiar species. In fresh water shells North America surpasses every other part of the globe, considerably over a thousand species, most of them Unio)iid&amp;lt;.e or fresh-water mussels, having been described. Subdivisions of the Nearctic Region. Owing to the researches of American zoologists these have been ascertained with tolerable accuracy, aud may be termed respectively the Californian, the Eocky Mountain, the Alleghany, and the Canadian sub-regions. The western or Californian sub-region comprises the narrow tract between the Sierra Nevada and the Pacific, not including Lower California, but extending northward into British Columbia to about 53 N. lat. It is characterized by a few very peculiar forms, and by a greater infusion of South American types than are found in similar latitudes on the east coast. Among Mammals Macrotus, a genus of vampyre bats ; among birds a cuckoo of the genus Geo- coccyx, and 2 genera of humming-birds (Selasphorus and Atthis); and among reptiles Lichanotus, a snake allied to the boas, are f&amp;gt;eo- tropical forms. California has also five or six peculiar genera of mammalia, Urotrichus, one of the moles, and Haploodon, forming a distinct family of liodents, being the most remarkable ; while