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and the Indian Peninsula; and Langaha (2 sp.), confined to Madagascar.
The Dipsadidae, or Nocturnal Tree Snakes, are distinguished from the last family by their dark colours and nocturnal habits. They are about equally abundant in the Oriental and Neotropical regions, less so in the Ethiopian, while only a single species extends to North Australia. The following are the best known genera :- . . - *
Dipsas, comprising all the Oriental species with one in AsiaMinor, and a few from the Moluccas, New Guinea, North Australia, West Africa, and Tropical America; Thamnodyastes, Tropidodipsas, and several others, from Tropical America; Dipsadoboa, from West Africa and Tropical America; Leptodeira, from Tropical and South Africa, South America, and Mexico; and Pythonodipsas, from Central Africa.
It is doubtful how far the three genera which constitute this family form a natural assemblage. We can therefore draw no safe conclusions from the peculiarity of their distribution— Scytale and Oxyrhopus being confined to Tropical America; while Hologerrhum inhabits the Philippine Islands.
The Lycodontidae, or Fanged Ground Snakes, are confined to the Ethiopian and Oriental regions, over the whole of which they range, except that they are absent from Madagascar and extend eastward to New Guinea. The genera have often a limited distribution:—
Lycodon ranges from India and Ceylon to China, the Philippines, and New Guinea; Tetragonosoma, the Malay Peninsula and Islands; Leptorhytaon and Ophites, India; Cercaspis, Ceylon; and Cyclocorus, the Philippines. The African genera are Boodon, Lycophidion, Holuropholis, Simocephalus, and Lamprophis, the latter being found only in South Africa. The species are nearly equally abundant in both regions, but no genus is common to the two.
The Amblycephalidae, or Blunt Heads, are very singularly distributed, being nearly equally divided between Tropical America and the eastern half of the Oriental region, as will be seen by the following statement of the distribution of the genera:
Amblycephalus (1 sp.), Malay Peninsula to Borneo and the Philippines; Pareas (3 sp.), Assam, China, Java, and Borneo; Asthenodipsas (1 sp.), Malacca; Leptognathus (6 sp.), Central and South America; and Anoplodipsas (1 sp.), supposed to come from New Caledonia, and, if so, furnishing a link, though a very imperfect one, between the disconnected halves of the family.
The Pythonidae, comprising the Rock Snakes, Pythons, and Boas, are confined to the tropics, with the exception of one species in California. They are very abundant in the Neotropical region, where nearly half the known species occur; the Australian region comes next, while the Oriental is the least prolific in these large serpents. The genera which have been described are very numerous, but they are by no means well defined. The following are the most important:-
Python is confined to the Oriental region; Morelia, Liasis, and Nardoa are Australian and Papuan; Emygrus is found in the Moluccas, New Guinea and the Fiji Islands; Hortulia is African; Sanzinia is peculiar to Madagascar; Boa, Epicrates, Corallus, Ungalia, and Eunecies are Tropical American; Chilabothrus is peculiar to Jamaica and Mexico; and Lichanotus to California. An extinct species belonging to this family has been found in the Brown-coal formation of Germany, of Miocene age.
The Erycidae, or Land Snakes, form a small but natural family, chiefly found in the desert zone on the confines of the Palaearctic, Oriental, and Ethiopian regions. They range from South Europe to West Africa and to Sikhim. The three genera are distributed as follows:— Cursoria (1 sp.), Afghanistan; Gongylophis (1 sp.), India and Sikhim; Erya (4 sp.), has the range of the entire family.
The Acrochordidae, or Wart Snakes, form a small and isolated group, found only in two sub-divisions of the Oriental region— the South Indian and the Malayan, and in New Guinea.
Acrochordus, inhabits Penang, Singapore, and Borneo; Chersydrus, Southern India and the Malay Peninsula, with a species recently discovered in New Guinea.
The Elapidae, or Terrestrial venomous Colubrine Snakes, are an extensive group, spread over the tropics of the whole world, but especially abundant in Australia, where half the known species occur, some of them being the most deadly of venomous serpents. In the Oriental region they are also abundant, containing amongst other forms, the well-known Cobras. The American species are almost equally numerous, but they all belong to one genus, and they are annulated with rings of various colours in a manner quite distinct from any other members of this family. The genera, which are all very distinct, are distributed as follows:— Diemenia, Acanthophis, Hoplocephalus, Brachiurophis, Tropidechis, Pseudechis, Cacophis, Pseudonaje, Denisonia, and Vermicella, are Australian, the first two ranging to the Moluccas and New Guinea; Ogmodon occurs in the Fiji Islands; Naja, Bungarus, Ophiophagus, Pseudonaje, Xenurelaps, Doliophis, Megaerophis, and Callophis are Oriental, one species of the latter genus being found in Japan, while an Ophiophagus has been discovered in New Guinea; Cyrtophis, Elapsoidea, and Poecilophis are African: Elaps is American, ranging as far north as South Carolina, but not to the West Indian Islands.