The four families into which the Chelonia are classed have all of them a wide distribution, though none are universal. The Ethiopian region seems to be the richest, as it possesses 3 of the four families, while no other region has more than 2; and it also possesses 7 peculiar genera. Next comes the Neotropical region with 2 families and 6 peculiar genera; the Australian with 3, and the Nearctic with 2 peculiar genera; while the Oriental and Palæarctic regions possess none that are peculiar. There are about 30 genera and 200 species in the whole order.
Fossil Chelonia.—The earliest undoubted remains of this order occur in the Upper Oolite. These belong to the Cheloniidæ and Emydidæ, which are also found in the Chalk. In the Tertiary beds Chelonia are more abundant, and the Trionychidæ now appear. The Testudinidæ are first met with in the Miocene formation of Europe and the Eocene of North America, the most remarkable being the gigantic Colossochelys Atlas of the Siwalik Hills. It appears, therefore, that the families of the order Chelonia were already specialised in the Secondary period, a fact which, together with their more or less aquatic habits, sufficiently accounts for their generally wide distribution. Species of Testudo, Emys, and Trionyx, are found in the Upper Miocene of the south of France.
AMPHIBIA.
Order I.—PSEUDOPHIDIA.
Family 1.—CÆCILIADÆ. (4 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 — | — — — — | — — — — | — 2 — — | 1. 2. 3 — | — — — — |
The Cæciliadæ are a curious group of worm-like Amphibia sparingly scattered over the three great tropical regions. The genera are,—Cæcilia, which inhabits West Africa, Malabar and South America; Siphonopsis, peculiar to Brazil and Mexico; Ichthyopsis, from Ceylon and the Khasya Mountains; and Rhinatrema from Cayenne.
Order II.—URODELA.
Family 2.—SIRENIDÆ. (1 Genus, 3 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. |
| — — — — | — — 3 — | — — — — | — — — — | — — — — | — — — — |