The Geographical Distribution of Animals/Chapter 19

The Typhlopidæ, or Blind Burrowing Snakes, are widely scattered over the warmer regions of the earth, but are most abundant in the Oriental and Australian regions, and least so in the Neotropical. They are absent from the Nearctic region; and in the Palæarctic are found only in South-eastern Europe and Japan.

The most extensive genus is Typhlops, comprising over 60 species, and having a range almost as extensive as the entire family. The other well characterised genera are:—

Typhlina (1 sp.), ranging from Penang to Java and Hong Kong; Typhline (1 sp.), the Cape of Good Hope; Dibamus (1 sp.), New Guinea.

The Tortricidæ, or Short-tailed Burrowing Snakes, are a small family, one portion of which ranges from India to Cambodja, and through the Malay islands as far as Celebes and Timor; these form the genus Cylindrophis. Another portion inhabits America, and consists of:—

Charina (1 sp.), found in California and British Columbia; and Tortrix (1 sp.), in Tropical America.

We have here a case of discontinuous distribution, indicating, either very imperfect knowledge of the group, or that it is the remnant of a once extensive family, on the road to extinction.

The curious nocturnal carnivorous Snake, forming the genus Xenopeltis, and the sole representative of this family, ranges from Penang to Cambodja, and through the Malay Islands to Celebes.

The Uropeltidæ, or Rough-tailed Burrowing Snakes, are strictly confined to Ceylon and the adjacent parts of Southern India, and would almost alone serve to mark out our second Oriental sub-region. The genera are:—

Rhinophis (7 sp.), Ceylon; Uropeltis (1 sp.), Ceylon; Silybura (8 sp.), Anamally Hills and Neilgherries; Plecturus (3 sp.), Neilgherries and Madras; and Melanophidium (1 sp.), the Wynand.

The Calamariidæ, or Dwarf Ground Snakes, are found in all warm parts of the globe, extending north into the United States as far as British Columbia and Lake Superior; but they are absent from the Palæarctic region, with the exception of a species found in Persia. The species are in a very confused state. The best characterised genera are the following:—

Calamaria (20 sp.), Persia, India to Java and the Philippine Islands, Celebes, and New Guinea; Rhabdosoma (18 sp.), Mexico and South America, and also the Malay Islands as far east as Amboyna, Timor, and New Guinea; Typhlocalamus (1 sp.), Borneo; Macrocalamus (1 sp.), India; Aspidura (3 sp.), India and Ceylon; Haplocerus (1 sp.), Ceylon; Streptophorus (3 sp.), Central and South America;—with a host of others of less importance or ill-defined.

The Oligodontidæ are a small family of Ground Snakes which have been separated from the Calamariidæ, and, with the exception of a few species, are confined to the Oriental region. The best characterised genera are:—

Oligodon (12 sp.), India, Ceylon, and Philippines; and, Simotes (24 sp.), India to China and Borneo. In addition to these, Achalinus is founded on a single species from Japan; and Teleolepis consists of three species from North and South America.

The Colubrine Snakes are universally distributed over the globe, and they reach the extreme northern limits of the order. They are, however, almost absent from Australia, being there represented only by a few species of Tropidonotus and Coronella in the northern and eastern districts. This great family consists of four divisions or sub-families: the Coronellinæ (20 genera, 100 species), the Colubrinæ (16 genera, 70 species), the Dryadinæ (7 genera, 50 species), and the Natricinæ (7 genera, 50 species). The more important genera of Colubridæ are the following:—

Ablabes, Coronella, Ptyas, Coluber, and Tropidonotus—all have a very wide distribution, but the two last are absent from South America, although Tropidonotus reaches Guatemala; Tomodon, Xenodon, Liopis, Stenorhina, Erythrolampus, Elapochrus, Callirhinus, Enophrys, and Dromicus—are confined to the Neotropical region; Hypsirhynchus, Cryptodacus, Jaltris, and Coloragia, are confined to the West Indian Islands; Chilomeniscus, Conophis, Pituophis, and Ischnognathus, to North America, the latter going as far south as Guatemala; Compsosoma, Zamenis, Zaocys, Atretium, Xenochrophys, and Herpetoreas, are peculiarly Oriental, but Zamenis extends into South Europe; Lytorhynchus, Rhamnophis, Herpetethiops and Grayia, are Ethiopian; Rhinechis is peculiar to Europe; Megablabes to Celebes, and Styporhynchus to Gilolo; Cyclophis, is found in the Oriental region, Japan, and North America; Spilotes, in the Nearctic and Neotropical regions; Xenelaphis in the Oriental, Ethiopian, and Palæarctic regions; Philodryas, Heterodon and Herpetodryas in America and Madagascar, the latter genus being also found in China.

The Homalopsidæ, or Fresh-water Snakes, have been separated from the Hydridæ by Dr. Günther, and they include some groups which have been usually classed with the Natricinæ. They are especially characteristic of the Oriental region, where considerably more than half the genera and species are found; next comes the Neotropical region which has 6 species; while none of the other regions have more than 4 or 5. It is to be observed that the Ethiopian species occur in West Africa only, and mostly constitute peculiar genera, so that in this family the separation of the Ethiopian and Oriental regions is very well marked. The best characterised genera of the family are the following:—

Cantoria (10 sp.), ranging from Europe to Japan, the Philippines, and Timor, with one species in Guinea; Hypsirhina (6 sp.), Bengal, China, and Borneo; Fordonia (3 sp.), Rangoon to Borneo and Timor; Homalopsis (2 sp.), Cambodja to Java; Cerberus (2 sp.), Ceylon and Siam, the Malay Islands, New Guinea, and North Australia; Herpeton (1 sp.), Siam; Ferania (1 sp.), Bengal to Penang; Pythonopsis (1 sp.), Borneo; Myron (2 sp.), India and North Australia; Homalophis (1 sp.), Borneo; Hipistes (1 sp.), Penang; Xenodermus (1 sp.), Java; Neusterophis and Limnophis, with one species each, are peculiar to West Africa; Helicops (2 sp.), North and South America; Farancia and Dimodes, with one species each, are from New Orleans; and a few others imperfectly known from Tropical America.

The Psammophidæ, or Desert Snakes, are a small group characteristic of the Ethiopian and Oriental regions, but more abundant in the former. The distribution of the genera is as follows:—

Psammophis (16 sp.), ranges from West Africa to Persia and Calcutta; Cœlopeltis (1 sp.), North and West Africa; Mimophis (1 sp.), Madagascar; Psammodynastes (2 sp.), Sikhim to Cochin China, Borneo and the Philippine Islands; and Dromophis (1 sp.), Tropical Africa.

The Rachiodontidæ are a small and very isolated group of snakes of doubtful affinities. The only genus, Dasypeltis (2 sp.), is confined to West and South Africa.

The Dendrophidæ, or Tree Snakes, are found in all the Tropical regions, but are most abundant in the Oriental. The genera are distributed as follows:—

Dendrophis ranges from India and Ceylon to the Pelew Islands and North Australia, and has one species in West Africa; Ahætulla is almost equally divided between Tropical Africa and Tropical America; Gonyosoma ranges from Persia to Java and the Philippines; Chrysopelea is found in India, Borneo, the Philippines, Amboyna, and Mysol; Hapsidrophis and Bucephalus are confined to Tropical Africa; and Ithycyphus (1 sp.), is peculiar to Madagascar.

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.

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.

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 Lycodontidæ, 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 Boædon, 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 Amblycephalidæ, 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 Pythonidæ, 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; Enygrus is found in the Moluccas, New Guinea and the Fiji Islands; Hortulia is African; Sanzinia is peculiar to Madagascar; Boa, Epicrates, Corallus, Ungalia, and Eunectes 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 Erycidæ, or Land Snakes, form a small but natural family, chiefly found in the desert zone on the confines of the Palæarctic, 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; Eryx (4 sp.), has the range of the entire family.

The Acrochordidæ, 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 Elapidæ, 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, Megærophis, 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 Pœcilophis are African: Elaps is American, ranging as far north as South Carolina, but not to the West Indian Islands.

The single genus Dendraspis, constituting the family, is confined to Tropical Africa.

This small family, consisting of the genus Atractaspis, is also confined to Africa, but has hitherto only been found in the West and South.

The Hydrophidæ, or Sea Snakes, are a group of small-sized marine serpents, abundant in the Indian and Australian seas, and extending as far west as Madagascar, and as far east as Panama. They are very poisonous, and it is probable that many species remain to be discovered. The genera are distributed as follows:—

Hydrophis (37 sp.), ranging from India to Formosa and Australia; Platurus (2 sp.), from the Bay of Bengal to New Guinea and New Zealand; Aipysurus (3 sp.), Java to New Guinea and Australia; Disteira (1 sp.), unknown locality; Acalyptus (1 sp.), South-west Pacific; Enhydrina (1 sp.), Bay of Bengal to New Guinea; Pelamis (1 sp.), Madagascar to New Guinea, New Zealand, and Panama; Emydocephalus (1 sp.), Australian Seas.

The Crotalidæ, or Pit Vipers, including the deadly Rattlesnakes, form a well-marked family of fanged serpents, whose distribution is very interesting. They abound most in the Oriental region, at least 5 of the genera and 20 species being found within its limits, yet they are quite unknown in the Ethiopian region—a parallel case to that of the Bears and Deer. A few species are peculiar to the eastern portion of the Palæarctic region, while the Nearctic is actually richer than the Neotropical region both in genera and species. This would point to the conclusion, that the group originated in the Indo-Chinese sub-region and spread thence north-east to North America, and so onward to South America, which, having been the last to receive the group, has not had time to develop it largely, notwithstanding its extreme adaptability to Reptilian life. The genera are divided among the several regions as follows:—

Craspedocephalus (7 sp.), Tropical America and the West Indian Islands; Cenchris, Crotalophorus, Uropsophorus, and Crotalus, inhabiting North America from Canada and British Columbia to Texas, one species (Crotalus horridus) extending into South America; Trimeresurus (16 sp.), all India from Ceylon to Assam, Formosa, the Philippines and Celebes; Peltopelor and Hypnale (1 sp. each), peculiar to India; Calloselasma (1 sp.), Siam; Atropos (1 sp.), Java and Borneo; Halys (3 sp.), peculiar to Tartary, Thibet, Japan, North China, and Formosa.

The Viperidæ, or True Vipers, are especially characteristic of the Palæarctic and Ethiopian regions, only one species being found over a large part of the Oriental region, and another reaching Central India. They are especially abundant in Africa, and the Palæarctic confines in South-western Asia. The common Viper ranges across the whole Palæarctic region from Portugal to Saghalien Island, reaching to 67° North Latitude, in Scandinavia, and to 58° in Central Siberia. The genera, according to Dr. Strauch's synopsis, are distributed as follows:—

Vipera (17 sp.), which has the range of the family, extending over the whole of the Palæarctic and Ethiopian regions, except Madagascar, and as far as Ceylon, Siam, and Java, in the Oriental region; Echis (2 sp.), inhabiting North Africa to Persia and to Continental India; and Atheris (3 sp.), confined to West Africa.

The Ophidia, being preeminently a Tropical order—rapidly diminishing in numbers as we go north in the Temperate Zone, and wholly ceasing long before we reach the Arctic Circle—we cannot expect the two Northern regions to exhibit any great variety or peculiarity. Yet in their warmer portions they are tolerably rich; for, of the 25 families of snakes, 6 are found in the Nearctic region, 10 in the Palæarctic, 13 in the Australian, 16 in the Neotropical, 17 in the Ethiopian, and no less than 22 in the Oriental, which last is thus seen to be by far the richest of the great regions in the variety of its forms of Ophidian life. The only regions that possess altogether peculiar families of this order, are the Ethiopian (3), and the Oriental (2); the usually rich and peculiar Neotropical region not possessing exclusively, any family of snakes; and what is still more remarkable, the Neotropical and Australian regions together, do not possess a family peculiar to them. Every family inhabiting these two regions is found also in the Oriental; and this fact, taken in connection with the superior richness of the latter region both in families and genera, would indicate that the Ophidia had their origin in the northern hemisphere of the Old World (the ancient Palæarctic region) whence they spread on all sides, in successive waves of migration, to the other regions. The distribution of the genera peculiar to, or highly characteristic of, the several regions is as follows:—

The Nearctic possesses 9; four of these belong to the Colubridæ, one to the Pythonidæ, and four to the Crotalidæ. The Palæarctic region has only 2 peculiar genera, belonging to the Colubridæ and Crotalidæ. The Ethiopian has 25, belonging to 11 families; four to Colubridæ, five to Lycodontidæ, and three to Elapidæ. The Oriental has no less than 50, belonging to 15 families; five are Colubridæ, five Uropeltidæ, twelve Homalopsidæ, six Lycodontidæ, three Amblycephalidæ, eight Elapidæ, and four Crotalidæ. The Australian has 16, belonging to three families only; eleven being Elapidæ, and four Pythonidæ. The Neotropical has about 24, belonging to eight families; ten are Colubridæ, six Pythonidæ, and the rest Dipsadidæ, Scytalidæ, Amblycephalidæ, Elapidæ, and Crotalidæ.

We find then, that in the Ophidia, the regions adopted in this work are remarkably distinct; and that, in the case of the Oriental and Ethiopian, the difference is strongly marked, a very large number of the genera being confined to each region. It is interesting to observe, that in many cases the affinity seems to be rather between the West Coast of Africa and the Oriental region, than between the East Coast and the plains of India; thus the Homalopsidæ—a highly characteristic Oriental family—occur on the West Coast of Africa only; the Dryiophidæ, which range over the whole Oriental region, only occur in Madagascar and West Africa in the Ethiopian; the genus Dipsas is found over all the Oriental region and again in West Africa. A cause for this peculiarity has been suggested in our sketch of the past history of the Ethiopian region, Vol. I. p. 288. In the Lycodontidæ, which are strictly confined to these two regions, the genera are all distinct, and the same is the case with the more widely distributed Elapidæ; and although a few desert forms, such as Echis and the Erycidæ, are common to Africa and the dry plains of India, this is evidently due to favourable climatic conditions, and cannot neutralise the striking differences in the great mass of the family and generic forms which inhabit the two regions. The union of Madagascar with the South-western part of the Oriental region under the appellation Lemuria, finds no support in the distribution of Ophidia; which, however, strikingly accords with the views developed in the Third Part of this work, as to the great importance and high antiquity of the Euro-Asiatic continent, as the chief land-centre from which the higher organisms have spread over the globe.

Fossil Ophidia.—The oldest known remains of Ophidia occur in the Eocene formation in the Isle of Sheppey; others are found in the Miocene (Brown Coal) of Germany, and in some Tertiary beds in the United States. Most of these appear to have been large species belonging to the Pythonidæ, so that we are evidently still very far from knowing anything of the earliest forms of this order. In some of the later Tertiary deposits the poison fangs of venomous species have been found; also a Colubrine snake from the Upper Miocene of the South of France.

The single species of Trogonophis, forming this family, is found only in North Africa.

Chirotes, the genus which constitutes this family, inhabits Mexico, and has also been found in Missouri, one of the Southern United States.

The Amphisbænidæ, which, in the opinion of Dr. Günther, are all comprised in the genus Amphisbæna, inhabit Spain and Asia Minor, North and Tropical Africa, South America as far as Buenos-Ayres and the West Indian Islands.

The small family of Lepidosternidæ has nearly the same distribution as the last, indicating a curious relationship between the Tropical parts of Africa and America. Lepidosternon and Cephalopeltis are American genera, while Monotrophis is African.

The Varanidæ, or Water Lizards, are most abundant in the Oriental region, whence they extend into the Austro-Malay Islands as far as New Guinea, and into Australia. Several species are found in Africa. Psammosaurus (1 sp.), is found in North Africa and North-western India; Monitor (18 sp.), has the range of the family; while Hydrosaurus (8 sp.) ranges from Siam to the Philippines, New Guinea, and Australia.

The genus Heloderma, which constitutes this family, is found in Mexico.

The Teidæ, or Teguexins—a group of Lizards allied to the European Lacertidæ, but with differently formed superciliary scales—are highly characteristic of the Neotropical region, abounding almost everywhere from Patagonia to the Antilles and Mexico, and extending northwards to California on the west and to Pennsylvania on the east. The most extensive genus is Ameiva, containing nearly 60 species and having the range of the entire family; Teius (3 sp.), inhabits Brazil and Mendoza; Callopistes (2 sp.), Chili; Centropyx (3 sp.), Paraguay to Alabama; Dicrodon (Peru); Monoplocus (Western Ecuador); with Acrantus, Acanthopyga, Emminia, Crocodilurus, Custa, and Ada, which each consist of a single species, and all inhabit Tropical America.

The Lacertidæ, or Land Lizards, are small-sized, terrestrial, non-burrowing lizards, very characteristic of the Palæarctic region, which contains more than half the known species, and of the adjacent parts of the Oriental and Ethiopian regions, but extending also to South Africa, to Java, and even to Australia. The best-defined genera are the following:—

Lacerta (10 sp.), ranging over all Central and South Europe to Poland, and farther north in Russia and Siberia, eastward to Persia, and southward to North and West Africa; Zootoca (8 sp.), has nearly the same range in Europe as the last genus, but has representatives in Madeira, South Africa, and Australia; Tachydromus (7 sp.) is widely scattered in Chinese Asia, Japan, Borneo, and West Africa; Acanthodactylus (10 sp.) is most abundant in North Africa, but has a species in South Africa, and two in Central India; Eremias (18 sp.) is found all over Africa, and also in the Crimea, Persia, Tartary and China; Psammodromus (2 sp.), is confined to Spain, France, and Italy; Ophiops (6 sp.), inhabits India, Persia, and Asia Minor to South Russia. Less strongly marked and perhaps less natural genera are the following:—

Thetia (1 sp.), Algiers; Teira (1 sp.), Madeira; Nucras (4 sp.), Caucasus and South Africa; Notopholis (4 sp.), South Europe and South Africa; Algira (3 sp.), North and South Africa; Scrapteira (1 sp.), Nubia; Aspidorhinus (1 sp.), Caspian district; Messalina (4 sp.), North Africa, Persia, and North-west India Cabrita (1 sp.), Central India; Pachyrhynchus (1 sp.), Benguela.

The Zonuridæ, or Land Lizards, characterised by a longitudinal fold of skin on each side of the body, have a very remarkable distribution. Their head-quarters is the Ethiopian region, which contains more than half the known genera and species, most of which are found in South Africa and several in Madagascar. Next to Africa the largest number of genera and species are found in Mexico and Central America, with a few in the Antilles, South America, and California, and even as far north as British Columbia. Three of the genera form a distinct sub-group—the Glass Snakes,—the four species composing it being located in North Africa, North America, South-eastern Europe, and the Khasya Hills.

The prominent fact in the distribution of this family is, that the mass of the genera and species form two groups, one in South Africa, the other in Mexico,—countries between which it would be difficult to imagine any means of communication. We have here, probably, an example of a once much more extensive group, widely distributed over the globe, and which has continued to maintain itself only in those districts especially adapted to its peculiar type of organization. This must undoubtedly have been the case with the genus Pseudopus, whose two species now inhabit South-eastern Europe and the Khasya Hills in Assam respectively.

The genera are,—Cordylus, Pseudocordylus, Platysaurus, Cordylosaurus, Pleurostrichus, and Saurophis, confined to South Africa; Zonurus, South and East Africa and Madagascar; Gerrhosaurus, ranges over the whole Ethiopian region; Cicigna is confined to Madagascar; Gerrhonotus (22 sp.), ranges from British Columbia, California, and Texas, to Cuba and South America, but is most abundant in Mexico and Central America; Abronia and Barissia, are two genera of doubtful distinctness, peculiar to Mexico; Ophisaurus (the Glass Snake) is found in the Southern United States as far as Virginia; the allied genus Hyalosaurus in North Africa; and Pseudopus, as above stated, in South-east Europe and the Khasya Hills.

The Chalcidæ are a small group of Lizards characteristic of Tropical America, one species extending into the United States.

The genera are Chalcis (6 sp.), ranging from Central America to Chili; two other species, which have been placed in distinct genera, inhabit North America and Peru.

The single species of Anadia, constituting this family, inhabits Tropical America.

The genus Heterodactylus, which constitutes this family, inhabits Brazil.

The single species of Iphisa, has been found only at Para in Equatorial America.

The genus Cercosaura, is known only from Brazil and Ecuador.

This family, consisting of a single species of the genus Chamæsaura, is confined to South Africa.

The Gymnophthalmidæ, or Gape-eyed Scinks, so called from their rudimentary eyelids, form a small group, which is widely and somewhat erratically distributed, as will be seen by the following account of the distribution of the genera:—

Lerista (1 sp.) and three other species for which Dr. Gray has established the genera—Morethria (1 sp.), and Menetia (2 sp.), are confined to Australia; Cryptoblepharus (4 sp.), is found in West Australia, Timor, New Guinea, the Fiji Islands, and Mauritius; Ablepharus (4 sp.), inhabits Eastern and South-eastern Europe, Persia, Siberia, West Africa, and the Bonin Islands; and Gymnophthalmus (3 sp.), is found in Brazil and the West Indies.

This small family of two-legged Lizards, comprising the genera Pygopus and Delma, is found only in Australia proper and Tasmania.

The genus Aprasia, constituting this family, is found in West and South Australia.

This family is also confined to Australia, the single genus, Lialis, inhabiting the Western and Northern districts.

The Scincidæ, or Scinks, are an extensive family of smooth-scaled lizards, frequenting dry and stony places, and almost universally distributed over the globe, being only absent from the cold northern and southern zones. The family itself is a very natural one, and it contains many natural genera; but a large number have been established which probably require careful revision. The following include the more important and the best established groups:—

Scincus (2 sp.), North Africa and Arabia; Hinulia (20 sp.), most of the Australian and Oriental regions; Cyclodina (1 sp.), Hombronia (1 sp.), and Lygosomella (1 sp.), all from New Zealand; Keneuxia (1 sp.), Philippines, Moluccas, and Papuan Islands; Elania (1 sp.) New Guinea; Carlia (2 sp.), North Australia and New Guinea; Mocoa (16 sp.), Australia and New Zealand, with species in Borneo, West Africa, and Central America; Lipinia (3 sp.), Philippine Islands and New Guinea; Lygosoma (12 sp.), Australia, New Caledonia, Pelew and Philippine Islands; Tetradactylus (1 sp.), Hemierges (2 sp.), Chelomeles (2 sp.), Omolepida (1 sp.), Lissolepis (1 sp.), Siaphos (1 sp.), Rhodona (3 sp.) Anomalpus (1 sp.), Soridia (2 sp.), and Ophioscincus (1 sp.) all confined to Australia; Cophoscincus (3 sp.), Philippine Islands, Celebes, and Queensland; Plestiodon (18 sp.), China and Japan, Africa, and America as far north as Pennsylvania and Nebraska; Eumeces (30 sp.), South Palæarctic, Oriental and Australian regions, to New Ireland and North Australia; Mabouya (20 sp.), Oriental region, Austro-Malaya, North Australia, the Neotropical region, and to Lat. 42° 30′ in North America; Amphixestus (1 sp.), Borneo; Hagria (1 sp.), and Chiamela (1 sp.), India; Senira (1 sp.), Philippine Islands; Brachymeles (2 sp.), Philippine Islands and Australia; Ophiodes (1 sp.), Brazil; Anguis (3 sp.), West Palæarctic region and South Africa; Tribolonotus (1 sp.), New Guinea; Tropidophorus (2 sp.), Cochin-China and Philippine Islands; Norbea (2 sp.), Borneo and Australia; Trachydosaurus (1 sp.), Australia; Cyclodus (8 sp.), Australia, Aru Islands, and Ceram; Silubosaurus (2 sp.), Egerina (2 sp.), and Tropidolepisma (6 sp.), all peculiar to Australia; Heteropus (7 sp.), Australia, Austro-Malaya, and Bourbon; Pygomeles (1 sp.), Madagascar; Dasia (1 sp.), Malaya; Euprepes (70 sp.), Ethiopian and Oriental regions, Austro-Malaya, South America (?); Celestus (9 sp.), peculiar to the Antilles, except a species in Costa Rica; Diploglossus (7 sp.), the Neotropical region;—with a number of other genera founded on single species from various parts of the world.

The snake-like Lizard constituting the genus Ophiomorus, is found in Southern Russia, Greece, and Algeria; while Zygnopsis having four weak limbs, has been recently discovered by Mr. Blanford in South Persia. The family is therefore confined to our Mediterranean sub-region.

The Sepidæ, or Sand-Lizards, are a very natural group, almost confined to the Ethiopian region, but extending into the desert country on the borders of the Oriental region, and into the south of the Palæarctic region as far as Palestine, Madeira, Spain, Italy, and even the South of France. The genera are:—

Seps (10 sp.), South Europe, Madeira, Teneriffe, Palestine, North Africa, South Africa and Madagascar; Sphenops (2 sp.), North Africa, Syria, West Africa; Scelotes (3 sp.), Angola to South Africa, Madagascar; Thyrus (1 sp.), Bourbon and Mauritius; Amphiglossus (1 sp.), Madagascar; Sphenocephalus (1 sp.), Afghanistan; and Sepsina (4 sp.), South-west Africa.

This small family of snake-like Lizards has a very curious distribution, being found in South and West Africa, Madagascar, Ceylon, and Ternate in the Moluccas. Acontias (4 sp.), is found in the four first-named localities; Nessia (2 sp.), is confined to Ceylon; Typhloscincus (1 sp.), to Ternate.

The Geckoes, or Wall-Lizards, form an extensive family, of almost universal distribution in the warmer parts of the globe; and they must have some exceptional means of dispersal, since they are found in many of the most remote islands of the great oceans,—as the Galapagos, the Sandwich Islands, Tahiti, New Zealand, the Loo-Choo and the Seychelle Islands, the Nicobar Islands, Mauritius, Ascension, Madeira, and many others. The following are the larger and more important genera:—

Oëdura (3 sp.), Australia; Diplodactylus (8 sp)., Australia, South Africa, and California; Phyllodactylus (8 sp.), widely scattered in Tropical America, California, Madagascar, and Queensland; Hemidactylus (40 sp.), all tropical and warm countries; Peropus (12 sp.), the Oriental region, Papuan Islands, Mauritius, and Brazil; Pentadactylus (7 sp.), Oriental region and Australia; Gecko (12 sp.), Oriental region to New Guinea and North Australia; Gehyra (5 sp.), Australia, New Guinea and Fiji Islands; Tarentola (7 sp.), North Africa, North America, Madeira, Borneo, South Africa; Phelsuma (6 sp.), Madagascar, Bourbon, and Andaman Islands; Pachydactylus (5 sp.), South and West Africa, and Ascension Island; Sphærodactylus (5 sp.), the Neotropical region; Naultinus, (6 sp.), New Zealand; Goniodactylus (5 sp.), Australia, Timor, South America and Algiers; Heteronota (4 sp.), Australia, Fiji Islands, New Guinea and Borneo; Cubina (4 sp.), the Neotropical region; Gymnodactylus (16 sp.), all warm countries except Australia; Phyllurus (3 sp.), Australia; Stenodactylus (4 sp.), North and West Africa, and Rio Grande in North America.

The remaining genera mostly consist of single species, and are pretty equally distributed over the various parts of the world indicated in the preceding list. Madagascar, the Seychelle Islands, Chili, the Sandwich Islands, South Africa, Tahiti, the Philippine Islands, New Caledonia, and Australia—all have peculiar genera, while two new ones have recently been described from Persia.

The extensive family of the Iguanas is highly characteristic of the Neotropical region, in every part of which the species abound, even as far as nearly 50° South Latitude in Patagonia. They also extend northwards into the warmer parts of the Nearctic region, as far as California, British Columbia, and Kansas on the west, and to 43° North Latitude in the Eastern States. A distinct genus occurs in the Fiji Islands, and one has been described as from Australia, and another from Madagascar, but there is some doubt about these. The most extensive genera are:—

Anolius (84 sp.), found in most parts of Tropical America and north to California; Tropidolepis (15 sp.), which has nearly the same range; Leiocephalus (14 sp.), Antilles, Guayaquil, and Galapagos Islands; Leiolæmus (14 sp.), Peru to Patagonia; Sceloporus (9 sp.), from Brazil to California and British Columbia, and on the east to Florida; Proctotretus (6 sp.), Chili and Patagonia; Phrynosoma (8 sp), New Mexico, California, Oregon and British Columbia, Arkansas and Florida; Iguana (5 sp.), Antilles and South America; Cyclusa (4 sp.), Antilles, Honduras, and Mexico.

Among the host of smaller genera may be noted:—

Brachylophus, found in the Fiji Islands; Trachycephalus and Oreocephalus, peculiar to the Galapagos; Oreodeira, said to be from Australia; Diplolæmus and Phymaturus, found only in Chili and Patagonia; and Callisaurus, Uta, Euphryne, Uma, and Holbrookia, from New Mexico and California. All the other genera are from various parts of Tropical America.

The extensive family Agamidæ—the Eastern representative of the Iguanas—is highly characteristic of the Oriental region, which possesses about half the known genera and species. Of the remainder, the greater part inhabit the Australian region; others range over the deserts of Central and Western Asia and Northern Africa, as far as Greece and South Russia. One genus extends through Africa to the Cape of Good Hope, and there are three peculiar genera in Madagascar, but the family is very poorly represented in the Ethiopian region. Many of these creatures are adorned with beautifully varied and vivid colours, and the little "dragons" or flying-lizards are among the most interesting forms in the entire order. The larger genera are distributed as follows:—

Draco (18 sp.), the Oriental region, excluding Ceylon; Otocryptis (4 sp.), Ceylon, North India, Malaya; Ceratophora (3 sp.), Ceylon; Gonyocephalus (8 sp.), Papuan Islands, Java, Borneo, Pelew Islands; Dilophyrus (7 sp.), Indo-Malaya and Siam; Japalura (6 sp.), Himalayas, Borneo, Formosa, and Loo Choo Islands; Sitana (2 sp.), Central and South India and Ceylon; Bronchocela (3 sp.), Indo-Malaya, Cambodja, and Celebes; Calotes (12 sp.), Continental India to China, Philippine Islands; Oriocalotes (2 sp.), Himalayas; Acanthosaura (5 sp.), Malacca and Siam; Tiaris (3 sp.), Andaman Islands, Borneo, Philippine and Papuan Islands; Physignathus (3 sp.), Cochin-China and Australia; Uromastix (5 sp.), South Russia, North Africa, Central India; Stellio (5 sp.), Caucasus and Greece to Arabia, High Himalayas and Central India; Trapelus (5 sp.), Tartary, Egypt, and Afghanistan; Phrynocephalus (10 sp.), Tartary and Mongolia, Persia and Afghanistan; Lophura (2 sp.), Amboyna and Pelew Islands; Grammatophorus (14 sp.), Australia and Tasmania; Agama (14 sp.), North Africa to the Punjaub, South Africa. The remaining genera each consist of a single species. Eight are peculiar to Australia, one to the Fiji Islands, one to the Aru Islands, three to Ceylon, five to other parts of the Oriental region, one to Persia, and one to South Russia.

The Chamæleons are an almost exclusively Ethiopian group, only one species, the common Chamæleon, inhabiting North Africa and Western Asia as far as Central India and Ceylon. They abound all over Africa, and peculiar species are found in Madagascar and Bourbon, as well as in the Island of Fernando Po.

The distribution of the Lacertilia is, in many particulars, strikingly opposed to that of the Ophidia. The Oriental, instead of being the richest is one of the poorest regions, both in the number of families and in the number of peculiar genera it contains; while in both these respects the Neotropical is by far the richest. The distribution of the families is as follows:—

The Nearctic region has 7 families, none of which are peculiar to it; but it has 3 peculiar genera—Chirotes, Ophisaurus, and Phrynosoma.

The Palæarctic region has 12 families, with two (Ophiomoridæ and Trogonophidæ, each consisting of a single species) peculiar; while it has 6 peculiar or very characteristic genera, Trogonophis in North Africa, Psammodromus in South Europe, Hyalosaurus in North Africa, Scincus in North Africa and Arabia, Ophiomorus in East Europe and North Africa, and Phrynocephalus in Siberia, Tartary, and Afghanistan. We have here a striking amount of diversity between the Nearctic and Palæarctic regions with hardly a single point of resemblance.

The Ethiopian region has 13 families, only one of which (the Chamæsauridæ, consisting of a single species) is altogether peculiar; but it possesses 21 peculiar or characteristic genera, 9 belonging to the Zonuridæ, 2 to the Sepidæ, 7 to the Geckotidæ, and 3 to the Agamidæ.

The Oriental region has only 8 families, none of which are peculiar; but there are 28 peculiar genera, 6 belonging to the Scincidæ, 1 to the Acontiadæ, 5 to the Geckotidæ, and 16 to the Agamidæ. Many lizards being sand and desert-haunters, it is not surprising that a number of forms are common to the borderlands of the Oriental and Ethiopian regions; yet the Sepidæ, so abundant in all Africa, do not range to the peninsula of India; and the equally Ethiopian Zonuridæ have only one Oriental species, found, not in the peninsula but in the Khasya Hills. The Acontiadæ alone offer some analogy to the distribution of the Lemurs, being found in Africa, Madagascar, Ceylon, and the Moluccas.

The Australian region has 11 families, 3 of which are peculiar; and it has about 40 peculiar genera in ten families, about half of these genera belonging to the Scincidæ. Only 3 families of almost universal distribution are common to the Australian and Neotropical regions, with one species of the American Iguanidæ in the Fiji Islands, so that, as far as this order is concerned, these two regions have little resemblance.

The Neotropical region has 15 families, 6 of which are peculiar to it, and it possesses more than 50 peculiar genera. These are distributed among 12 families, but more than half belong to the Iguanidæ, and half the remainder to the Teidæ,—the two families especially characteristic of the Neotropical region. All the Nearctic families which are not of almost universal distribution are peculiarly Neotropical, showing that the Lacertilia of the former region have probably been derived almost exclusively from the latter.

On the whole the distribution of the Lacertilia shows a remarkable amount of specialization in each of the great tropical regions, whence we may infer that Southern Asia, Tropical Africa, Australia, and South America, each obtained their original stock of this order at very remote periods, and that there has since been little intercommunication between them. The peculiar affinities indicated by such cases as the Lepidosternidæ, found only in the tropics of Africa and South America, and Tachydromus in Eastern Asia and West Africa, may be the results either of once widely distributed families surviving only in isolated localities where the conditions are favourable,—or of some partial and temporary geographical connection, allowing of a limited degree of intermixture of faunas. The former appears to be the more probable and generally efficient cause, but the latter may have operated in exceptional cases.

These date back to the Triassic period, and they are found in most succeeding formations, but it is not till the Tertiary period that forms allied to existing genera occur. These are at present too rare and too ill-defined to throw much light on the geographical distribution of the order.

The singular and isolated genus Hatteria—the "Tuatara" or fringed lizard—which alone constitutes this family, has peculiarities of structure which separate it from both lizards and crocodiles, and mark it out as an ancestral type, as distinct from other living reptiles as the Marsupials are from other Mammalia. It is confined to New Zealand, and is chiefly found on small islands near the north-east coast, being very rare, if not extinct, on the main land. A fossil reptile named Hyperodapedon, of Triassic age, has been found in Scotland and India, and is supposed by Professor Huxley to be more nearly allied to Hatteria than to any other living animal.

The Gavials are long-snouted Crocodiles with large front teeth, and canines fitting in notches of the upper jaw. They consist of two genera, Gavialis (1 sp.), inhabiting the Ganges; Tomistoma (2 sp.), found in the rivers of Borneo and North Australia.

The true Crocodiles, which have the canines in notches, and the large front teeth in pits in the upper jaw, are widely distributed over the tropical regions of the globe, inhabiting all the rivers of Africa, the shores and estuaries of India, Siam, and eastward to North Australia. Other forms inhabit Cuba, Yucatan, and Guatemala, to Ecuador and the Orinooko. Four species are Asiatic, one exclusively Australian, three African, and four American. These have been placed in distinct groups, but Dr. Günther considers them all to form one genus, Crocodilus.

The Alligators, which are distinguished by having both the large front teeth and the canines fitting into pits of the upper jaw, are confined to the Neotropical, and the southern part of the Nearctic regions, from the lower Mississippi and Texas through all Tropical America, but they appear to be absent from the Antilles. They are all placed by Dr. Günther in the single genus, Alligator.

These animals, being few in number and wholly confined to the tropical and sub-tropical regions, are of comparatively little interest as regards geographical distribution. America possesses both Crocodiles and Alligators; India, Crocodiles and Gavials; while Africa has Crocodiles only. Both Crocodiles and Gavials are found in the northern part of the Australian region, so that neither of the three families are restricted to a single region.

The existing families of the order date back to the Eocene period in Europe, and the Cretaceous in North America. In the south of England, Alligators, Gavials and Crocodiles, all occur in Eocene beds, indicating that the present distribution of these families is the result of partial extinction, and a gradual restriction of their range—a most instructive fact, suggesting the true explanation of a large number of cases of discontinuous distribution which are sometimes held to prove the former union of lands now divided by the deepest oceans. In more ancient formations, a number of Crocodilian remains have been discovered which cannot be classed in any existing families, and which, therefore, throw no light on the existing distribution of the group.

The Testudinidæ, including the land and many fresh-water tortoises, are very widely distributed over the Old and New worlds, but are entirely absent from Australia. They are especially abundant in the Nearctic region, as far north as Canada and British Columbia, and almost equally so in the Neotropical and Oriental regions; in the Ethiopian there is a considerable diminution in the number of species, and in the Palæarctic they are still less numerous, being confined to the warmer parts of it, except one species which extends as far north as Hungary and Prussia. The genera are:—

Testudo (25 sp.), most abundant in the Ethiopian region, but also extending over the Oriental region, into South Europe, and the Eastern States of North America; Emys (64 sp.), abundant in North America and over the whole Oriental region, less so in the Neotropical and the Palæarctic regions; Cinosternon (13 sp.), United States and California, and Tropical America; Aromochelys (4 sp.), confined to the Eastern States of North America; Staurotypus (2 sp.), Guatemala and Mexico; Chelydra (1 sp.), Canada to Louisiana; Claudius (1 sp.), Mexico; Dermatemys (3 sp.), South America, Guatemala, and Yucatan; Terrapene (4 sp.), Maine to Mexico, Sumatra to New Guinea, Shanghae and Formosa—a doubtfully natural group; Cinyxis (3 sp.), Pyxis (1 sp.), Chersina (4 sp.), are all Ethiopian; Dumerilia (1 sp.), is from Madagascar only.

The Chelydidæ, or fresh-water tortoises with imperfectly retractile heads, have a remarkable distribution in the three great southern continents of Africa, Australia, and South America; the largest number of species being found in the latter country. The genera are:—

Peltocephalus (1 sp.), Podocnemis (6 sp.), Hydromedusa (4 sp.), Chelys (1 sp.), and Platemys (16 sp.), inhabiting South America from the Orinooko to the La Plata, the latter genus occurring also in Australia and New Guinea; Chelodina (5 sp.), Chelemys (1 sp.), and Elseya (2 sp.) from Australia; while Sternotheres (6 sp.), and Pelomedusa (3 sp.), inhabit Tropical and South Africa and Madagascar.

The distribution of the Trionychidæ, or Soft Tortoises, is very different from that of the Chelydidæ, yet is equally interesting. They abound most in the Oriental region, extending beyond it to Northern China and Japan. In the Nearctic region they are only found in the Eastern States, corresponding curiously to the distribution of plants, in which the affinity of Japan to the Eastern States is greater than to California. The Trionychidæ are also found over the Ethiopian region, but not in Madagascar.

The genera are,—Trionyx (17 sp.), which extends over the whole area of the family as above indicated; Cycloderma (5 sp.), peculiar to Africa; Emyda (3 sp.), the peninsula of India, Ceylon, and Africa.

—All the warm and tropical Seas.

The Marine Turtles are almost universally distributed. Dermatochelys (1 sp.), is found in the temperate seas of both the Northern and Southern Hemispheres; Chelone (4 sp.), ranges over all the tropical seas—C. viridis, the epicureans' species, inhabiting the Atlantic, while C. imbricata which produces the "tortoiseshell" of commerce is found in the Indian and Pacific oceans.

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.