The Geographical Distribution of Animals, Volume 2 / With a study of the relations of living and extinct faunas as elucidating the past changes of the Earth's surface

by Alfred Russel Wallace

Family 22.—DACTYLETHRIDÆ. (1 Genus, 2 Species.)

General Distribution.
Neotropical Sub-regions.	Nearctic Sub-regions.	Palæarctic Sub-regions.	Ethiopian Sub-regions.	Oriental Sub-regions.	Australian Sub-regions.
— — — —	— — — —	— — — —	1. 2. 3 —	— — — —	— — — —

The Dactylethridæ are Toads with maxillary teeth but no tongue, and with enormously dilated sacrum. The species of Dactylethra are natives of West, East, and South Africa.

General Remarks on the Distribution of the Amphibia.

The Amphibia, as here enumerated, consist of 22 families, 152 genera, and nearly 700 species. Many of the families have a very limited range, only two (Ranidæ and Polypedatidæ) being nearly universal; five more extend each into five regions, while no less than thirteen of the families are confined to one, two, or three regions each. By far the richest region is the Neotropical, possessing 16 families (four of them peculiar) and about 50 peculiar or very characteristic genera. Next comes the Australian, with 11 families (one of which is peculiar) and 16 peculiar genera. The Nearctic region has no less than 9 of the families (two of them peculiar to it) and 15 peculiar genera, 13 of which are tailed Batrachians which have here their metropolis. The other three regions have 9 families each; the Palæarctic has no peculiar family but no less than 15 peculiar genera; the Ethiopian 1 family and 12 genera peculiar to it; and the Oriental, 19 genera but no family confined to it.

It is evident, therefore, that each of the regions is well characterised by its peculiar forms of Amphibia, there being only a few genera, such as Hyla, Rana, and Bufo which have a wide range. The connection of the Australian and Neotropical regions is well shown in this group, by the Phryniscidæ, Hylidæ, and Discoglossidæ, which present allied forms in both; as well as by the genus Liopelma of New Zealand, allied to the Bombinatoridæ of South America, and the absence of the otherwise cosmopolitan genus Rana from both continents. The affinity of the Nearctic and Palæarctic regions is shown by the Proteidæ, which are confined to them, as well as by the genus Triton and almost the whole of the extensive family of the Salamandridæ. The other regions are also well differentiated, and there is no sign of a special Ethiopian Amphibian fauna extending over the peninsula of India, or of the Oriental and Palæarctic regions merging into each other, except by means of genera of universal distribution.

Fossil Amphibia.—The extinct Labyrinthodontia form a separate order, which existed from the Carboniferous to the Triassic period. No other remains of this class are found till we reach the Tertiary formation, when Newts and Salamanders as well as Frogs and Toads occur, most frequently in the Miocene deposits. The most remarkable is the Andrias scheuchzeri from the Miocene of Œningen, which is allied to Sieboldia maxima the great salamander of Japan.

CHAPTER XX.

THE DISTRIBUTION OF THE FAMILIES OF FISHES, WITH THE RANGE OF SUCH GENERA AS INHABIT FRESH WATER.

Sub-class I.—TELEOSTEI.