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North Australia; Gehyra (5 sp.), Australia, New Guinea and Fiji Islands; Tarentola (7 sp.), North Africa, North America, Madeira, Borneo, South Africa; Phelsuma (6 sp.), Madagascar, Bourbon, and Andaman Islands; Pachydactylus (5 sp.), South and West Africa, and Ascension Island; Sphcerodactylus (5 sp.), the Neotropical region; Navltinus, (6 sp.), New Zealand; Goniodactylus (5 sp.), Australia, Timor, South America and Algiers; Heteronota (4 sp.), Australia, Fiji Islands, New Guinea and Borneo; Cubina (4 sp.), the Neotropical region; Gyvi.nodactylus (16 sp.), all warm countries except Australia; Phyllurus (3 sp.), Australia; Stenodactylus (4 sp.), North and West Africa, and Rio Grande in North America.
The remaining genera mostly consist of single species, and are pretty equally distributed over the various parts of the world indicated in the preceding list. Madagascar, the Seychelle Islands, Chili, the Sandwich Islands, South Africa, Tahiti, the Philippine Islands, New Caledonia, and Australia—all have peculiar genera, while two new ones have recently been described from Persia.
The extensive family of the Iguanas is highly characteristic of the Neotropical region, in every part of which the species abound, even as far as nearly 50° South Latitude in Patagonia. They also extend northwards into the warmer parts of the Nearctic regiou, as far as California, British Columbia, and Kansas on the west, and to 43° North Latitude in the Eastern States. A distinct genus occurs in the Fiji Islands, and one has been described as from Australia, and another from Madagascar, but there is some doubt about these. The most extensive genera are :—
Anolivs (84 sp.), found in most parts of Tropical America and north to California; Tropidolepis (15 sp.), which has nearly the same range; Leiocephalus (14. sp.), Antilles, Guayaquil, and Galapagos Islands; Zeiolcemus (14 sp.), Peru to Patagonia; Scdoporus (9 sp.), from Brazil to California and British Columbia, and on the east to Florida; Proctotretus (6 sp.), Chili and Patagonia; Phrynosoma (8 sp.), New Mexico, California, Oregon and British Columbia, Arkansas and Florida; Iguana (5 sp.), Antilles and South America; Oyclusa (4 sp), Antilles, Honduras, and Mexico.
Among the host of smaller genera may be noted:— Brachylophus, found in the Fiji Islands; Trachycephalus and Oreocephalus, peculiar to the Galapagos; Oreodeira, said to be from Australia ; Diplolarmus and Phymaturus, found only in Chili and Patagonia; and Callisaurus, Uta, JEuphryne, Uma, and Holbrookia, from New Mexico and California. All the other genera are from various parts of Tropical America.
Family 51.—AGAMID^E (42 Genera, 156 Species.)
The extensive family Agamidae—the Eastern representative of the Iguanas—is highly characteristic of the Oriental region, which possesses about half the known genera and species. Of the remainder, the greater part inhabit the Australian region; others range over the deserts of Central and Western Asia and Northern Africa, as far as Greece and South Russia. One genus extends through Africa to the Cape of Good Hope, and there are three peculiar genera in Madagascar, but the family is very poorly represented in the Ethiopian region. Many of these creatures are adorned with beautifully varied and vivid colours, and the little "dragons" or flying-lizards are among the most interesting forms in the entire order. The larger genera are distributed as follows :—
Draco (18 sp.), the Oriental region, excluding Ceylon; Otocryptis (4 sp.), Ceylon, North India, Malaya; Ceratophora (3 sp.), Ceylon; Gonyocephalus (8 sp.), Papuan Islands, Java, Borneo, Pelew Islands; Dilophyrus (7 sp.), Indo-Malaya and Siam ; Japalura (6 sp.), Himalayas, Borneo, Formosa, and Loo Choo Islands ; Sitana (2 sp.), Central and South India and Ceylon ; Bronchocela (3 sp.), Indo-Malaya, Cambodja, and Celebes; Calotes (12 sp.), Continental India to China, Philippine Islands; Oriocalotes (2 sp.), Himalayas ; Acanthosaura (5 sp.), Malacca and Siam; Tiaris (3 sp.), Andaman Islands, Borneo, Philippine and Papuan Islands; Physignathus (3 sp.), Cochin-China and Australia ; Uromastix (5 sp.), South Russia, North Africa, Central India ; Stellio (5 sp.), Caucasus and Greece to Arabia, High Himalayas and Central India ; Trapelus (5 sp.), Tartary, Egypt, and Afghanistan ; Phrynocephalus (10 sp.), Tartary and Mongolia, Persia and Afghanistan; Lophura (2 sp.), Amboyna and Pelew Islands; Grammatophorus (14 sp.), Australia and Tasmania ; Agama (14 sp.), North Africa to the Punjaub, South Africa. The remaining genera each consist of a single species. Eight are peculiar to Australia, one to the Fiji Islands, one to the Aru Islands, three to Ceylon, five to other parts of the Oriental region, one to Persia, and one to South Russia.
FAMILY 52.-CHAMÆLEONIDÆ. (1 Genus, 30 Species.)
The Chamæleons are an almost exclusively Ethiopian group, only one species, the common Chamæleon, inhabiting North Africa and Western Asia as far as Central India and Ceylon. They abound all over Africa, and peculiar species are found in Madagascar and Bourbon, as well as in the Island of Fernando Po.
General Remarks on the Distribution of the Lacertilia.
The distribution of the Lacertilia is, in many particulars, strikingly opposed to that of the Ophidia. The Oriental, instead of being the richest is one of the poorest regions, both in the number of families and in the number of peculiar genera it contains; while in both these respects the Neotropical is by far the richest. The distribution of the families is as follows :—
The Nearctic region has 7 families, none of which are peculiar to it; but it has 3 peculiar genera—Chirotes, Ophisaurus, and Phrynosoma.
The Palaearctic region has 12 families, with two (Ophiomoridae and Trogonophidae, each consisting of a single species) peculiar; while it has 6 peculiar or very characteristic genera, Trogonophis in North Africa, Psammodromvs in South Europe, Hyalosaurus in North Africa, Scincus in North Africa and Arabia, Ophiomorus in East Europe and North Africa, and Phrynocephalus in Siberia, Tartary, and Afghanistan. We have here a striking amount of diversity between the Nearctic and Palaearctic regions with hardly a single point of resemblance.
The Ethiopian region has 13 families, only one of which (the Chamsesauridae, consisting of a single species) is altogether peculiar; but it possesses 21 peculiar or characteristic genera, 9 belonging to the Zonuridae, 2 to the Sepidae, 7 to the Geckotidae, and 3 to the Agamidse.
The Oriental region has only 8 families, none of which are peculiar; but there are 28 peculiar genera, 6 belonging to the Scincidae, 1 to the Acontiadae, 5 to the Geckotidae, and 16 to the Agamidae. Many lizards being sand and desert-haunters, it is not surprising that a number of forms are common to the borderlands of the Oriental and Ethiopian regions; yet the Sepidae, so abundant in all Africa, do not range to the peninsula of India; and the equally Ethiopian Zonuridae have only one Oriental species, found, not in the peninsula but in the Khasya Hills. The Acontiadce alone offer some analogy to the distribution of the Lemurs, being found in Africa, Madagascar, Ceylon, and the Moluccas.
The Australian region has 11 families, 3 of which are peculiar; and it has about 40 peculiar genera in ten families, about half of these genera belonging to the Scincidae. Only 3 families of almost universal distribution are common to the Australian and Neotropical regions, with one species of the American Iguanidae in the Fiji Islands, so that, as far as this order is concerned, these two regions have little resemblance.
The Neotropical region has 15 families, 6 of which are peculiar to it, and it possesses more than 50 peculiar genera. These are distributed among 12 families, but more than half belong to the Iguanidse, and half the remainder to the Teidse,—the two families especially characteristic of the Neotropical region. All the Nearctic families which are not of almost universal distribution are peculiarly Neotropical, showing that the Lacertilia of the former region have probably been derived almost exclusively from the latter.
On the whole the distribution of the Lacertilia shows a remarkable amount of specialization in each of the great tropical regions, whence we may infer that Southern Asia, Tropical Africa, Australia, and South America, each obtained their original stock of this order at very remote periods, and that there has since been little intercommunication between them. The peculiar affinities indicated by such cases as the Lepidosternidse, found only in the tropics of Africa and South America, and Tachydrmnus in Eastern Asia and West Africa, may be the results either of once widely distributed families surviving only in isolated localities where the conditions are favourable,—or of some partial and temporary geographical connection, allowing of a limited degree of intermixture of faunas. The former appears to be the more probable and generally efficient cause, but the latter may have operated in exceptional cases.
Fossil Lacertilia. These date back to the Triassic period, and they are found in most succeeding formations, but it is not till the Tertiary period that forms allied to existing genera occur. These are at present too rare and too ill-defined to throw much light on the geographical distribution of the order.