tween Australia and the Oriental Region or whether 

 there was only a series of stepping-stone islands by 

 which dispersal took place. The Celebes, the Moluc- 

 cas, and the Lesser Sunda Islands lie intermediate 

 between the Oriental and Australian Regions and 

 derive their fauna from both directions. 



The Australo-Papuan region is marked by the 

 absence of most groups of placental mammals, al- 

 though some have been introduced. The original 

 mammalian fauna consisted chiefly of monotremes, a 

 diversity of marsupials, murid rats and mice, and 

 bats. Well represented among birds are parrots and 

 parakeets, cockatoos, lories, honey-eaters, birds of 

 paradise, pigeons, megapodes, and kingfishers. Note- 

 worthy is the presence of the emu (Australia), 

 cassowary (New Guinea and adjacent islands), lyre- 

 bird, scrub-bird, and kiwi (New Zealand), and the 

 absence of woodpeckers. Reptiles are well repre- 

 sented in the region, including Sphenodon, in New 

 Zealand. Salamanders and true frogs are absent or 

 scarce, but tree frogs occur in a great variety of 

 species. The fresh-water fish fauna is scant, but in- 

 cludes the dipnoan lungfish Epiceratodus. Among 

 the invertebrates, relict crayfishes of the family Para- 

 stacidae and a variety of land snails are of interest. 

 Except some bats, there are no native mammals in 

 New Zealand. The bird fauna is poor, with several 

 flightless forms. In general, as one proceeds east- 

 ward and northward away from Australia and New 

 Guinea the variety of animal life found on the iso- 

 lated islands progressively decreases, but because of 

 the isolation of the islands, many peculiar endemic 

 forms are found. 



Neotropical region 



The Neotropical region making up the Neo- 

 gaeic realm includes all of South America and the 

 West Indies, and extends through Central America 

 to include the southern lowland part of Mexico. 



The fauna of this region includes a large number 

 of endemic forms. Among the edentates, the sloths, 

 armadillos, and anteaters are largely peculiar, al- 

 though one species of armadillo extends north to 

 Texas and east to Florida. There is a variety of marsu- 

 pials present that doubtlessly entered South America 

 from the north, although only one living marsupial 

 occurs at present in the United States. The hystricoid 

 rodents include the tree-porcupines, guinea pigs, 

 agoutis, chinchillas, and others, of which only the 

 porcupine has spread into North America. Prehen- 

 sile-tailed monkeys and marmosets are characteristic, 

 and tapirs occur here as well as in the Oriental region. 

 Insectivores are largely absent. 



The avifauna is rich and includes the tinamous, 

 hoatzin. trumpeters, sun-bitterns, cariamas, seed- 



snipe, rhea, puffbirds, toucans, hummingbirds, and 

 several unique families of passerines. Altogether, the 

 Neotropical region has about 2500 species of breeding 

 birds ; Ethiopian region, 1750 : Palaearctic sub-region, 

 1110; Nearctic sub-region, 750; Australia and Tas- 

 mania together, 650. 



Reptiles are well represented, and among am- 

 phibians the tree frogs Hylidae reach their greatest 

 diversification of species. Toads are present, but only 

 a few true frogs and a few salamanders among the 

 tailed forms. Among fishes, the catfishes, characins, 

 and the eels are well represented, and one of the 

 three remaining genera of lungfishes, Lepidosiren, 

 occurs. Minnows are absent. 



Islands in the West Indies have a reduced fauna, 

 species of which appear to be variously derived from 

 Central and North America. Of mammals, only ro- 

 dents, bats, and the peculiar insectivore Solenodon 

 are found. Fossil evidence, however, indicates a 

 richer mammalian fauna in the past, which apparently 

 arrived by an over-water route, perhaps on rafts 

 (Simpson 1956). Except in Trinidad, the fresh- 

 water fish that occur in the West Indies are also 

 tolerant of salt water. 



The occurrence of many related forms in South 

 America, Australia, and Africa, and the absence or 

 poor representation of those forms, even as fossils, 

 in North America and Eurasia has made the ex- 

 planation of how they became distributed difificult. 

 Land bridges across the South Atlantic and South 

 Pacific have been postulated, but the idea is not gen- 

 erally accepted at the present time. The continental 

 drift theory attempted to explain the distributions. 

 An intervening connection at least of South America, 

 Australia, and New Zealand at some time in the 

 geological past with a large continent, Antarctica, in 

 the south polar regions has been suggested (Glenny 

 1954). There is some evidence that Antarctica at 

 one time had a warmer climate, but its secrets are 

 now largely buried under many meters of snow and 

 ice and must await development of new exploratory 

 tools. 



Ethiopian region 



All the rest of the world, outside of the Noto- 

 gaeic and Neogaeic realms, belongs to the Arctogaeic 

 realm. Especially characteristic of this realm are the 

 presence of ungulates, insectivores, catarrhine mon- 

 keys, and ganoid and cyprinoid fishes. Arctogaea is 

 divided into three main regions. In the Ethiopian 

 region is included all of Africa south of the northwest 

 corner ; and, since the Red Sea is of relatively recent 

 origin and is not an important barrier, the southern 

 part of Arabia. In the northeastern quarter of the 

 realm the fauna reflects a mingling with the fauna 



270 Geographic distribution of communities 



