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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 subfamily 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 Limacidae, 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
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 forestplain of the Amazons, extending from Paranaiba on the north coast of Brazil (long. 42° W.) to Zamora, in the province of Loja (lat. 4° ş., long. 79° W.), high up in the Andes, on the west ;a distance in a straight line of more than 2,500 English miles,
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 subregion 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 op the Pacific coast as far as to about 5° of south latitude, belong to south temperate America, or the sub-region of the Åndes.
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 (Hydrochærus) the largest known rodent, belonging to the Caviidæ; the larger ant-eaters (Myrmecophaga); sloths of the genus Bradypus ; 2 genera of armadillos (Dasypodidae); 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
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;