The Geographical Distribution of Animals/Chapter 19.2

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.

The genus Siren, consisting of eel-like Batrachians with two anterior feet and permanent branchiæ, inhabits the South-Eastern States of North America from Texas to Carolina.

The Proteidæ have four feet and persistent external branchiæ. The two genera are,—Proteus (1 sp.), found only in caverns of Central Europe; and Menobranchus, which are like newts in form, and inhabit the Eastern States of North America.

The genus Amphiuma, or Murænopsis, consists of slender eel-like creatures with four rudimentary feet, and no external branchiæ. The species inhabit the Southern United States from New Orleans to Carolina.

These are large Salamanders of repulsive appearance, found only in Eastern Asia and the Eastern United States. The genera are,—Sieboldia (2 sp.), Japan and north-west China; Menopoma = Protonopsis (2 sp.), Ohio and Alleghany rivers.

The Salamandridæ, of which our common Newts are characteristic examples, form an extensive family highly characteristic of the North Temperate regions, a few species only extending into the Neotropical region along the Andes to near Bogota, and one into the Oriental region in Western China. The genera, as arranged by Dr. Strauch, are as follows:—

Salamandra (2 sp.), Central and South Europe and North Africa; Pleurodeles (1 sp.), Spain, Portugal, and Morocco; Bradybates (1 sp.), Spain; Triton (16 sp.), all Europe except the extreme north, Algeria, North China and Japan, Eastern States of North America, California and Oregon; Chioglossa (2 sp.), Portugal and South Europe; Salamandrina (1 sp.), Italy to Dalmatia; Ellipsoglossa (2 sp.), Japan; Isodactylium (2 sp.), East Siberia; Onychodactylus (1 sp.), Japan; Amblystoma (21 sp.), Nearctic region from Canada and Oregon to Mexico, most abundant in Eastern States; Ranodon (1 sp.), Tartary and North-east China; Dicamptodon (1 sp.), California; Plethodon (5 sp.), Massachusetts to Louisiana, and Vancouver's Island to California; Desmognathus (4 sp.), Eastern United States south of latitude 43°; Anaides (1 sp.), Oregon and Northern California; Hemidactylium (2 sp.), South-eastern United States and Southern California; Heredia (1 sp.), Oregon and California; Spelerpes (18 sp.), Eastern United States from Massachusetts to Mexico, Guatemala, Costa Rica and Andes of Bogota, with a species in South Europe; Batrachoseps (2 sp.), South-eastern United States and California; Tylotriton (1 sp.), Yunan in West China.

The Rhinophrynidæ are Toads with imperfect ears and a tongue which is free in front. The single species of Rhinophrynus, is a native of Mexico.

The Phryniscidæ, or Toads with imperfect ears and tongue fixed in front, are widely distributed over the warmer regions of the earth, but are most abundant in the Neotropical region and Australia, while only single species occur in the Old World. The genera are:—

Phryniscus (7 sp.), from Costa Rica to Chili and Monte Video; Brachycephalus (1 sp.), Brazil; Pseudophryne (3 sp.), Australia and Tasmania; Hemisus (1 sp.), Tropical Africa; Micrhyla (1 sp.), Java.

The Hylaplesidæ are Toads with perfect ears, and they seem to be confined to the Neotropical region. The only genus, Hylaplesia (5 sp.), inhabits Brazil, Chili, and the Island of Hayti.

The rather extensive family of the Bufonidæ, which includes our common Toad, and is characterised by prominent neck glands and tongue fixed in front, is almost universally distributed, but is very rare in the Australian region; one species being found in Celebes and one in Australia. The genera are:—

Kalophrynus (2 sp.), Borneo; Bufo (58 sp.), has the range of the entire family, except Australia; Otilophus (1 sp.), South America; Peltaphryne (1 sp.), Porto Rico; Pseudobufo (1 sp.), Malay Peninsula; Schismaderma (1 sp.), Natal; Notaden (1 sp.), East Central Australia.

The Xenorhinidæ may be characterised as Toads with perfect ears and tongue free in front. The only species of Xenorhina is a native of New Guinea.

The Engystomidæ are Toads without neck-glands and with the tongue tied in front. They are most abundant in the Oriental and Neotropical regions, especially in the latter, which contains about half the known species, with isolated species in Australia, Africa, and the Southern States of North America. They appear to be the remnant of a once extensive and universally distributed group, which has maintained itself in two remote regions, but is dying out everywhere else. The genera are:—

Engystoma (9 sp.), Carolina to La Plata, with one species in South China; Diplopelma (3 sp.), South India to China and Java; Cacopus (2 sp.), Central India; Glyphoglossus (1 sp.), Pegu; Callula (4 sp.), Sikhim, Ceylon, China, and Borneo; Brachymerus (1 sp.), South Africa; Adenomera (1 sp.), Brazil; Pachybatrachus (1 sp.), Australia; Breviceps (2 sp.), South and West Africa; Chelydobatrachus (1 sp.), West Australia; Hypopachus (1 sp.), Costa Rica; Rhinoderma (1 sp.), Chili; Atelopus (1 sp.), Cayenne and Peru; Copea (1 sp.), South America; Paludicola (1 sp.), New Granada.

The Bombinatoridæ are a family of Frogs which have imperfect ears and no neck-glands, and they have a very peculiar and interesting distribution, being confined to Central and South Europe, the southern part of South America, and New Zealand. They consist of many isolated groups forming five separate sub-families. The genera are:—

Bombinator, Central Europe and Italy; Pelobates and Didocus, Central Europe and Spain; Telmatobius (2 sp.), Peru and Brazil; Alsodes, Chonos Archipelago; Cacotus, Chili; Liopelma, New Zealand; Nannophryne, Straits of Magellan.

The Plectromantidæ, which are Frogs with neck-glands, and the toes but not the fingers dilated, consists of a single species of the genus Plectromantis. It inhabits the region west of the Andes, and south of the Equator.

The Alytidæ are Frogs with neck-glands and undilated toes. They are most abundant in the Ethiopian region, with a few species in the Nearctic and Australian regions, and one in Europe and Brazil respectively. The genera are:—

Alytes (1 sp.), Central Europe; Scaphiopus (5 sp.), California to Mexico and the Eastern States; Hyperolius (29 sp.), all Africa, and two in New Guinea and North Australia; Helioporus (1 sp.), in Australia; Nattereria (1 sp.), Brazil.

The Pelodryadæ are Tree Frogs with neck-glands, and are confined to the Australian and Neotropical regions. The genera are:—

Phyllomedusa (3 sp.), South America to Paraguay; Chirodryas, Australia; and Pelodryas (3 sp.), Moluccas, New Guinea and Australia.

The Hylidæ are glandless Tree Frogs with a broadened sacrum. They are most abundant in the Neotropical region, which contains more than two-thirds of the species; about twenty species are Australian; six or seven are Nearctic, reaching northward to Great Bear Lake; while one only is European, and one Oriental. The genera are:—

Hyla (62 sp.), having the range of the whole family; Hylella (1 sp.), Ololygon (1 sp.), Pohlia (2 sp.), Triprion (1 sp.), Opisthodelphys (1 sp.), and Nototrema (4 sp.), are South American; while Trachycephalus (8 sp.), is peculiar to the Antilles, except one South American species; Pseudacris (1 sp.), ranges from Georgia, United States, to Great Bear Lake; Litoria (7 sp.), is Australian and Papuan, except one species in Paraguay; Ceratohyla (4 sp.), is only known from Ecuador.

The Polypedatidæ, or glandless Tree Frogs with narrowed sacrum, are almost equally numerous in the Oriental and Neotropical regions, more than forty species inhabiting each, while in the Ethiopian there are about half this number, and the remainder are scattered over the other three regions, as shown in the enumeration of the genera:—

Ixalus (16 sp.), Oriental, except one in Japan, and one in Western Polynesia; Rhacophorus (7 sp.), and Theloderma (1 sp.), are Oriental; Hylarana (10 sp.), Oriental, to the Solomon Islands and Tartary, Nicobar Islands, West Africa, and Madagascar; Megalixalus (1 sp.), Seychelle Islands; Leptomantis (1 sp.), Philippines; Platymantis (5 sp.), New Guinea, Philippines, and Fiji Islands; Cornufer (2 sp.), Java and New Guinea; Polypedates (19 sp.), mostly Oriental, but two species in West Africa, one Madagascar, two Japan, one Loo-Choo Islands, and one Hong Kong; Hylambates (3 sp.), Hemimantis (1 sp.), and Chiromantis (1 sp.), are Ethiopian; Rappia (13 sp.), is Ethiopian, and extends to Madagascar and the Seychelle Islands; Acris (2 sp.), is North American; Elosia (1 sp.), Epirhixis (1 sp.), Phyllobates (9 sp.), Hylodes (26 sp.), Hyloxalus (1 sp.), Pristimantis (1 sp.), Crossodactylus (1 sp.), Calostethus (1 sp.), Strabomantis (1 sp.), and Leiyla (1 sp.), are Neotropical, the last two being Central American, while species of Hylodes and Phyllobates are found in the West Indian Islands.

The Ranidæ, or true Frogs, are characterised by having simple undilated toes, but neither neck-glands nor dilated sacrum. They are almost cosmopolitan, extending to the extreme north and south from the North Cape to Patagonia, and they are equally at home in the tropics. They are perhaps most abundant in South America, where a large number of the genera and species are found; the Ethiopian region comes next, while they are rather less abundant in the Oriental and Australian regions; the Nearctic region has much less (about 12 species), while the Palæarctic has only five, and these two northern regions only possess the single genus Rana. The genera are distributed as follows:—

Rana (60 sp.), ranges all over the world, except Australia and South America, although it extends into New Guinea and into Mexico and Central America; it is most abundant in Africa. Pyxicephalus (7 sp.), extends over the whole Ethiopian region, Hindostan, the Himalayas, and Japan; Cystignathus (22 sp.), is mainly Neotropical, but has three species Ethiopian. All the other genera are confined to single regions. The Neotropical genera are:—Odontophrynus (1 sp.), Pseudis (1 sp.), Pithecopsis (1 sp.), Ensophleus (1 sp.), Limnocharis (1 sp.), Hemiphractus (1 sp.), all Tropical South American east of Andes; Ceratophrys (5 sp.), Panama to La Plata; Cycloramphus (1 sp.), West Ecuador and Chili; Pleurodema (6 sp.), Venezuela to Patagonia; Leiuperus (12 sp.), Mexico and St. Domingo to Patagonia; Hylorhina (1 sp.), Chiloe. The Australian genera are:—Myxophyes (1 sp.), Queensland; Platyplectrum (2 sp.), Queensland and West Australia; Neobatrachus (1 sp.), South Australia; Limnodynastes (7 sp.), and Crinia (11 sp.), Australia and Tasmania. The Oriental genera are:—Dicroglossus (1 sp.), Western Himalayas; Oxyglossus (2 sp.), Siam to Java, Philippines and China; Hoplobatrachus (1 sp.), Ceylon; Phrynoglossus (1 sp.), Siam. The Ethiopian genera are:—Phrynobatrachus (1 sp.), Stenorhynchus (1 sp.), both from Natal.

The Discoglossidæ, or Frogs with a dilated sacrum, are remarkable for the number of generic forms scattered over a large part of the globe, being only absent from the Nearctic and the northern half of the Neotropical regions, and also from Hindostan and East Africa. The genera are:—

Chiroleptes (4 sp.), Australia; Calyptocephalus (1 sp.), allied to the preceding, from Chili; Cryptotis (1 sp.), Australia; Asterophrys (2 sp.), New Guinea and Aru Islands; Xenophrys (1 sp.), Eastern Himalayas; Megalophrys (2 sp.), Ceylon and the Malay Islands; Nannophrys (1 sp.), Ceylon; Pelodytes (1 sp.), France only; Leptobrachium (1 sp.), Java; Discoglossus (1 sp.), Vienna to Algiers; Laprissa (1 sp.), Latonia (1 sp.), Palæarctic region; Arthroleptis (2 sp.), West Africa and the Cape; Grypiscus (1 sp.), South Brazil.

The Pipidæ are toads without a tongue or maxillary teeth, and with enormously dilated sacrum. The only species of Pipa is a native of Guiana.

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.

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.