in favour of a land-connexion between Neogaea and Notogaea
cannot have the weight attributed to it by Mr W. J. Sinclair.
The typical Edentata (sloths, anteaters and armadillos) are at the present day practically confined to Neogaea where they have existed from the date of the Santa Cruz beds of Patagonia (which are probably of Miocene age). A few armadillos, however, have penetrated into Texas; and in the Pleistocene epoch several representatives of the extinct ground-sloths (Megatheriidae) and a glyptodon, or giant armadillo, also ranged into North America. The group is, however, essentially Neogaeic. Among the monkeys the Cebidae, or American monkeys, and their relatives the Hapalidae, or marmosets, are likewise peculiar to Neogaea, where they date from the Santa Cruz epoch. The vampire-bats, or Phyllostomatidae, are likewise peculiar to this realm, and are doubtless also endemic. With the exception of a few shrew-mice, which have evidently entered from the north, continental Neogaea is at the present day devoid of Insectivora. It is, however, very note-worthy that one peculiar family (Solenodontidae) of the order, apparently nearly allied to the Malagasy Centetidae (tenrecs), occurs in the West Indies, while the extinct Necrolestes, believed to be near akin to the African golden moles (Chrysochloridae), is found in the Santa Cruz beds. Rodents of more or less peculiar types are highly characteristic of Neogaea and for the most part date from the Santa Cruz epoch. Among these the Caviidae, Chinchillidae and Octodontidae are peculiar to this realm, while the Capromyidae are common to the Ethiopian region of Arctogaea, but are unknown elsewhere.
Ungulates are in the main very poorly represented in Neogaea and include only the llama group (guanaco, &c.), tapirs, and certain small or medium-sized deer related to North American types. Palaeontological evidence tells us that these, like certain peculiar genera of horses now extinct (such as Hippidium) and mastodons, were comparatively recent intruders into the realm from the north. On the other hand, Neogaea at the date of the deposition of the Santa Cruz beds was the home of certain endemic groups of ungulates, such as the Toxodontia and Litopterna, some of the representatives of which (Toxodon and Macrauchenia) flourished during the Pleistocene Pampean epoch.
Of the Carnivora, the civet group (Viverridae) is absent, and the representatives of the dog tribe (Canidae), bears (Ursidae), of which there is only a single existing representative, cats (Felidae), and probably raccoons (Procyonidae), must be regarded as intruders from the north, although several genera of the last-named group are peculiar to the area. In the Santa Cruz epoch the place of these modern specialized Carnivora was taken by marsupial-like creodonts, such as Prothylacinus.
In birds Neogaea is especially rich and contains more than a score of family groups unknown elsewhere. Several of these, such as the tyrant-birds (Tyrannidae), manakins (Pipridae), chatterers (Cotingidae), ant-thrushes (Formicariidae), the oven-bird group (Dendrocolaptidae) , plant-cutters(Phytotomidae) , and wren-thrushes (Pteroptychidae), belong to a low and generalized type of the perching, or passerine, group. Among the so-called picarian birds, which are likewise a generalized type, the big-billed toucans (Rhamphasiidae), puff-birds (Bucconidae), jacamars (Galbulidae), motmots (Momotidae), and the vast assemblage of humming-birds (Trochilidae) are in the main peculiar to this realm, although some of the last- named family wander to the northward in summer. The condors (Cathartidae), form a highly characteristic Neogaeic family; while the hoatzin (Opisthocomus) represents another. Of the higher forms of perching-birds the quit-quits (Coerebidae), greenlets (Vireonidae), the hang-nests and many other representatives of the Icteridae, and the tanagers (Tanagridae) are exclusively Neogaeic ; while crows, starlings, thrushes, warblers and flycatchers are either rare or wanting, although the finches are abundant. Parrots are numerous, and represented by peculiar forms such as the macaws (Ara) and conures or ordinary South American parrots (Conurus). Very characteristic of the realm, and unknown elsewhere are the curassows and guans (Cracidae) among the game-birds, the chajas, or screamers (Palamedeidae), the trumpeters (Psophiidae), sun-bitterns (Eurypygidae), and the seriema (Cariamidae). Allied apparently to the last is Phororhachos, a giant extinct bird from the Santa Cruz beds with a skull nearly as large as that of a pony. The tinamous (Tinamidae), possibly an annectant type between game-birds and the ostrich group, and the rheas or American ostriches (Rheidae) are likewise exclusively Neogaeic. It may be added that the distribution of all the members of the ostrich group affords a strong argument in favour of a former union of the southern continents, especially as their earliest known representative is African.
Among reptiles, the tortoises, with the exception of representatives of the terrestrial genus Testudo, all belong to the Pleurodira, and include several peculiar generic types such as Chelys (matamata) and one, Podocnemis, common to Madagascar. The occurrence in the Tertiary of Patagonia of a representative of Miolania, else-where known only from the Pleistocene of Queensland, has been already mentioned. A number of snakes of the boa group (Boinae) occur in the realm, to which the genus Eunectes anacondas) is restricted; but Boa itself, like Podocnemis among the tortoises, is common to Neogaea and Madagascar. The blind burrowing-snakes of the family Glauconiidae occur throughout the warmer parts of the realm, and are also found in Africa and south-western Asia. The caimans or South American alligators (Caiman) are solely Neogaean; the iguanas (Iguanidae) are mainly peculiar to the realm, although a few inhabit North America, and there are two outlying genera in Madagascar and a third in Fiji. The tejus (Tejidae) are wholly Neogaean. The Xantusiidae are exclusively Central American and Antillean; while the Amphisbaenidae are practically restricted to Neogaea and Africa. On the other hand, Lacertidae, Varanidae and Agamidae are absent. Tailed amphibians are unknown south of Central America; but the region is the home of several peculiar types of toads, such as Pipa (Surinam toad) belonging to an otherwise Ethiopian section, and the majority of the family Cystignathidae, as exemplified by the horned toad and the escuerso (Ceratophrys), the remainder of the group being Australian.
Freshwater fishes are very abundant in Neogaea, where they are represented by a number of peculiar generic and certain family types; some of the members have developed the remarkable habit of feeding upon the floating fruits abundant in the rivers of the tropical forest-districts.
The electric eels (Gymnotidae) are peculiar to the waters of Neogaea, as are certain other groups, such as the armoured cat-fishes (Loricariidae), while true cat-fishes (Siluridae) are extremely abundant. Perhaps, however, the most remarkable feature of the fish-fauna of Neogaea is its affinity to that of the Ethiopian region. Among the lung-fishes the family Lepidosirenidae is, for example, restricted to the two areas, with one genus in each, as is also the family Characinidae. Much the same may be said of the Cichlidae, which have, however, representatives in the Malagasy and Oriental regions; and the Cyprinodontidae, which are extremely abundant in Neogaea (where certain of their representatives are separated by some naturalists as a distinct family, Poeciliidae) likewise present the same general type of distribution, although their area includes the southern fringe of the Palaearctic sub-region and a considerable portion of the Oriental region.
As regards the past history of Neogaea, Professor Carl Eigenmann, writing in the Popular Science Monthly for June 1906, observes that "in the earliest Tertiary tropical America consisted of two land-areas, Archiguiana and Archamazonia, separated by the lower valley of the Amazon, which was still submerged. There was a land-mass, Hellenis, between Africa and South America, possibly in contact with Guiana and some point in tropical Africa. This land-mass, which was inhabited, among other things, by fishes belonging to the families Lepidosirenida (lung-fishes), Poeciliidae, Characinidae, Cichlidae and Siluridae (cat-fishes), sank beneath the surface of the ocean, forcing the fauna in two directions, towards Africa and towards South America, exterminating all types not moved to the east or to the west. From these two rudiments have developed the present diverse faunas of Africa and South America, each reinforced by intrusions from the ocean and neighbouring land-areas, and by autochthonous development within its own border.… The connexion between Africa and South America existed before the origin of present genera, and even before the origin of some of the present families and sub-families, some time before the early Tertiary. There has never been any exchange between Africa and South America since that time."
This connexion between Neogaea and Africa was doubtless a continuation of the old Jurassic equatorial land-belt to which allusion has been already made; freshwater fishes being probably a group of earlier radiation than mammals. Perhaps the distribution of the reptilian genera common to Neogaea and Madagascar may be explained in the same manner, although tortoises apparently identical with Podocnemis occur in the Eocene of Europe (as well as in that of Africa and India), so that this group may have radiated from the north. Whether the evidence of the Cystignathidae among the amphibians and of the extinct Miolania among chelonians is also evidence of the persistence of the Jurassic connexion between Neogaea and Notogaea till a considerably later epoch must, for the present, be left an open question. The distribution of other families of lizards is, however, not in favour of such a connexion, the Lacertidae and Agamidae being confined to the Old World, inclusive of Australia but exclusive of Madagascar, while the cosmopolitan Scincidae, so abundant in Notogaea, are extremely scarce in Neogaea.
Reverting to the mammalian fauna, its evidence, combined with that of geology, indicates that during the greater portion of the Tertiary period South America was isolated from North America, and inhabited by its autochthonous fauna of monkeys, marmosets, sloths, ground-sloths, ant-eaters, armadillos, glyptodonts, toxodonts, macrauchenias (together with certain other peculiar ungulates), rodents, marsupials and creodonts, as well as by Phororhachos, rheas, tinamous and probably some of the other groups of birds now peculiar to the area. This state of things continued till the later Miocene or Pliocene epoch, during some portion of which a connexion was established with North America by way of the isthmus of Darien. By means of this new land-bridge a certain proportion of the autochthonous fauna of Neogaea was enabled
