| General Distribution. | |||||
 | |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — 2 — 4 | 1. 2. 3. 4 | 1 — — — |
The Dryiophidæ, or Whip Snakes, are a very well characterised family of slender, green-coloured, arboreal serpents, found in the three tropical regions but absent from Australia, although they just enter the Australian region in the island of Celebes. In Africa they are confined to the West Coast and Madagascar. The genera are:—
Dryiophis (4 sp.), Tropical America and West Africa; Tropidococcyx (1 sp.), Central India; Tragops (4 sp.), Bengal to China, the Philippines, Java, and Celebes; Passerita (2 sp.), Ceylon and the Indian Peninsula; and Langaha (2 sp.), confined to Madagascar.
Family 13.—DIPSADIDÆ. (11 Genera, 45 Species.)
| General Distribution. | |||||
| |||||
| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — 2 — — | 1. 2. 3 — | 1. 2. 3. 4 | 1. 2 — — |
The Dipsadidæ, 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 Asia-Minor, 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.
Family 14.—SCYTALIDÆ. (3 Genera, 10 Species.)
| General Distribution. | |||||
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| Neotropical Sub-regions. | Nearctic Sub-regions. | Palæarctic Sub-regions. | Ethiopian Sub-regions. | Oriental Sub-regions. | Australian Sub-regions. |
| — 2. 3 — | — — — — | — — — — | — — — — | — — — 4 | — — — — |
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.