Distribution of Reptiles—Frogs and Toads—Snakes, Saurians, and
Tortoises.
REPTILES, more than any other class of animals, show the partial
distribution of animated beings, because, being unable to travel to any
great distance, they have remained in the places wherein they were
originally stationed; and as they inhabit deserts, forests, and
uncultivated ground, they have not been disturbed by man, who has only
destroyed some individuals, but has not diminished the number of
species, which is probably the same as ever it was. Few of the mammalia
hybernate, or fall into a torpid state in winter, except the bear,
marmot, bats, and some others. Their fat supplies the carbon consumed by
the oxygen during their feeble and imperceptible respiration, and is
wasted by the time the warm weather returns, which rouses them from
their lethargy, thin and extenuated. But reptiles, being colder-blooded,
bury themselves in the ground, and hybernate during the winter in cold
and temperate climates. In hot countries, they fall into a state of
torpor during the dry season, so that they have no occasion to wander,
either on account of temperature or want of sustenance; and the few that
do migrate in quest of food always return to their old haunts. As the
blood of reptiles receives only a small part of the oxygen they inhale,
little heat and strength are generated; consequently they are
cold-blooded, and, for the most part, sluggish in their motions, which,
however, are more varied than in quadrupeds; but as some reptiles, such
as tortoises and lizards, breathe more frequently than others, there
are, consequently, great differences in their energy and sensibility.
The order of Reptiles is divided by naturalists into four classes,
commencing in the ascending order:—1. Batracians or frogs, toads, and
salamanders; 2. Ophidians or serpents; 3. Saurians, lizards, chameleons,
crocodiles; and 4. Emydians or tortoises, and turtles. With very few
exceptions they are oviparous; they partake of both terrestrial and
aquatic forms, and many are amphibious: they all increase in numbers
towards the equator, and few live in cold climates; but they can endure
a cold winter better than a cool summer. Frogs and salamanders inhabit
the banks of the M’Kenzie river in North America, where the mean
temperature is between 7° and 8° of Fahrenheit; the thermometer in
winter even sinks to 90° below the freezing point. The southern limit of
reptiles, so far as it is known, is in 50° S. lat., where a frog was
found on the banks of the river Santa Cruz.
The number of species of reptiles in the torrid zone is at least double
that in the temperate; Australia has fewer than Europe, and of all
places in the Old World, Java is richest in reptiles. America possesses
more than half of all the species, the maximum being in Brazil, but
everyone of them is peculiar to that continent alone.
The Batrachians approach nearest to the nature of fishes, and form a
link between land and water animals. As tadpoles they have tails and no
feet, but when full-grown they generally acquire feet and lose their
tails. Besides, in that early stage they are aquatic and breathe by
gills, like fishes; but in a state of maturity they breathe by lungs
like quadrupeds, though some of the genera always retain their gills and
tails, and some never acquire feet. These animals have the power of
retarding and accelerating their respiration without stopping the
circulation of their blood, so that they can resist heat and cold to a
certain degree—a power most remarkable in the salamander, which forms
part of this class, so varied in appearance and nature. Some, as toads
and frogs, imbibe a quantity of water, which is evaporated through their
skin more or less quickly. This keeps them at the temperature of the
medium they live in, and the air they inhale through the skin is as
necessary to their existence as that which they breathe.
The group of toads and frogs consists of four families, which have four
feet, but without tails; namely, frogs, hylas or rainettes, toads, and
pipæ. Frogs, which are amphibious, have no nails on their toes, and
their hind legs are longer than the fore, and webbed, consequently
better fitted for swimming and jumping, which they do by leaps. There
are 16 genera, and above 50 species, so that they are more numerous and
more varied than any other reptile. Of the hyla or tree-frog there are
60 species, all of the most vivid and brilliant tints, and several
colours are frequently united on the same animal. They mostly live on
high trees, and their webbed feet have little cushions at the points of
their toes, forming a kind of sucker, by means of which they can squeeze
out the air from under their feet, and, by the pressure of the
atmosphere, they adhere firmly to the under side of the smoothest leaf,
exactly on the same principle by which flies walk on the ceiling of a
room. The bufo, or toad, is the ugliest of the race; many are hideous,
with swollen bodies, wart-like excrescences, and obtuse toes. They
seldom go into water, but frequently marshy, damp places, and only
crawl, whereas the frog and hyla leap. They are much fewer than either
of the other two families; only 30 species are known. The pipæ are also
toads of a still more disgusting form, and are distinguished from their
congeners by not having an extensile tongue. All these reptiles produce
noises, which are exceedingly varied; they croak in concert, following a
leader, and when he is tired another takes his place. One of the North
American frogs croaks in bands; one band begins, another answers, and a
third replies, till the noise is heard at a great distance; a pause then
takes place, after which the croaking is renewed. Mr. Darwin mentions a
little musical hyla at Rio de Janeiro, which croaks a kind of harmony in
different notes.
Toads and frogs are found in almost all parts of the earth, though very
unequally and partially distributed. America has more than all the other
countries taken together, and Europe the fewest. Six species of frogs,
one rainette, and two toads, are European; and all, except four of the
frogs, are also found in Asia and Africa. The Rana temporaria lives at
the height of 7700 feet in the Pyrenees, and near the snow-line on the
Alps.
The law of circumscribed distribution is strongly marked in Asia; for of
ten species of frogs peculiar to that continent, three only are in the
mainland, two are confined to Japan, and, of the five that are Javanese,
one is also common to Amboina, and the other four to Bengal. The eight
species of rainettes, or tree-frogs, are still more limited in their
domicile; five of them are in Java only, and one in Japan; and the Hyla
viridis is in Asia Minor. There are nine species of toad peculiar to
Asia.
None of these reptiles exist in the Galapagos Archipelago, nor in any of
the innumerable islands in Oceanica, and there are very few in
Australia, but all peculiar. In Africa there are eight species of frogs,
two or three of rainettes, and two of toads. One of the two species of
pipa, more horrid in appearance than any toad, is very common at the
Cape of Good Hope, and there only.
The great extent of marshes, rivers, and forests, together with the heat
of the climate, make America the very home of reptiles of this kind, and
there they grow to a greater size than anywhere else: 23 species of
frog, 27 species of tree-frog or rainette, and 21 of toads, are
indigenous in that continent, not one of which is the same with any of
those in the Old World; and most of those in South America are different
from those in the northern part of the continent, though they are
sometimes replaced by analogous kinds. All these reptiles have abodes,
with fixed demarcations, often of small extent. The pipa, or toad of
Surinam, is the most horrid of the tribe; the Bufo agua, of Brazil, 10
or 12 inches long, and the Rana pipiens, of Carolina, are the largest.
The second family of this class of reptiles have tails and feet, as the
salamanders, which are very like lizards in their general form, having a
long round or flattened tail and four feet. Some are terrestrial, and
some are aquatic; the former are known as salamanders or newts, the
latter as tritons. Both are met with in Europe, but the greater number
are American. The amphibious genera of Amphiuma Menopoma and Syren,
possessing both lungs and gills, are American; the latter are peculiar
to the marshes and rice-grounds of Carolina, and the Axolotl is only
found in the Lake of Mexico: they are very like eels with two feet. The
Proteus anguinus, of a light flesh-colour, has four little feet and a
flat tail, and has been found nowhere but in the dark subterraneous
caverns in Carniola.
The third group of this order of Batrachians are the Cæciliæ, of which
there are only eight species, all inhabitants of the warm parts of Asia,
Africa, and America. They have a cylindrical body, without feet or neck,
and move exactly as the serpent, so they seem to form the link between
these reptiles and the class of frogs and toads.
There are serpents in all hot and temperate countries, but they abound
most in intertropical regions. Java contains 56 species, which is a
greater number comparatively than any other country, while in Borneo not
one has been found. Those in Japan are peculiar. Wherever snakes exist,
there also are some of the venomous kinds, but they are fewer,
specifically and individually, than is generally supposed. Of 263
species, only 57 are venomous, or about one in five, although that
proportion is not everywhere the same. In sterile, open countries, the
proportion of venomous snakes is greater than in those that are covered
with vegetation. Thus, in New Holland, seven out of ten species are
poisonous; and in Africa, one of every two or three individuals is
noxious. In general, however, the number of harmless individuals is
twenty times as great as the number of the poisonous.
The three great families of venomous serpents are the colubriform or
adder-shaped snakes, sea-serpents, and the triangular-headed snakes.
The adder-formed snakes are divided into three genera, the elaps, which
are slender like a cord, with a small head, and of brilliant colours.
There are four species in South America, of which two are confined to
Guiana, and one to Surinam, while the other is found everywhere from
Brazil to Carolina. There is only one in Africa, three in Australia, and
the rest are in limited districts in tropical Asia, especially in
Sumatra and Java; and an entire genus is found only in India, and the
islands of Ceylon and Java. The hooded snakes (or Cobra Capello) are the
best known of this family, especially the spectacled or dancing snake of
the Indian jugglers, which is common everywhere from Malabar to Sumatra,
and two other species are only found in Sumatra and Java. The three or
four African species are chiefly at the Cape of Good Hope and on the
Gold Coast; but the most celebrated is that generally known as the
Egyptian asp, which has been tamed by magicians of ancient and modern
times, and is frequently figured in Egyptian monuments; it derives some
of its celebrity from Cleopatra’s death. Two of the family inhabit New
Holland, one of which is spectacled, like, but of a different species
from, that in India.
All the seven species of sea-snakes are very venomous, and more
ferocious than any other. They frequent the Indian Ocean in shoals from
Malabar to the Philippine Islands and the Bay of Bengal; they never
enter fresh water.
The third venomous family consists of the triangular-headed serpents,
rattle-snakes, and vipers. The first are of a hideous aspect,—a large
head, broad at the base like a heart, a wide mouth, with their hooked
poisonous fangs strongly developed. They quietly watch their prey till
it is within reach, then dart upon it, and inflict the deadly wound in a
moment; the yellow viper of the French West India islands, the
Trigonocephalus lanceolatus, being amongst the dangerous snakes in
existence. One species in the Old World is to be met with everywhere
from Ceylon to the Phillippine Islands; one is a native in Sumatra,
Timor, and Celebes; the rest are narrowly limited in their abode; two
are confined to Java alone. Ceylon, Sumatra, Japan, and Tartary, have
each a species of these serpents peculiar to itself.
The rattle-snakes are all American—two in the warm districts of North
America, and two in the intertropical parts of South America. One of the
latter, however, has a hard horn at the end of its tail, instead of a
rattle, and sometimes grows to the length of 10 feet, being, with the
Trigonocephalus, the longest of the venomous snakes.
Vipers come farther north than any other of the noxious tribe: two are
Asiatic, though one is also common to Africa, which, however, has four
peculiar to itself; and the only venomous serpents in Europe are three
species of viper, one of which is also spread over the neighbouring
parts of Asia and Africa. The common viper inhabits all central Europe
and temperate Asia, even to Lake Baikal, in the Altaï Mountains: it is
also found in England and Sweden, but it does not go farther west than
the Seine, nor does it pass the Alps. One which frequents dry soils, in
the south-east of Europe, is in Styria, Greece, Dalmatia, and Sicily;
and the aspic viper, which lives on rocky ground, inhabits France
between the Seine and the Pyrenees, Switzerland, Italy, and Sicily.
There are six families of innocuous serpents, consisting of numerous
species. Four of the families are terrestrial; their species are very
limited in their domicile, the greater number being confined to some of
the islands of the Indian Archipelago, Ceylon, or to circumscribed
districts in tropical Asia, Africa, and America. Nine or ten species are
European, some of which are also found in Asia and Africa.
Tree-serpents of various genera and numerous species live only in the
great tropical forests of Asia and America, especially in the latter.
They are long and slender, the head for the most part ending in a sharp
point, and generally green, though there are some of brighter colours;
many of these serpents are fierce, though not venomous; some feed on
birds, which they watch hanging by the tail from a bough.
In all temperate and warm countries abounding in lakes and rivers,
fresh-water snakes are numerous; some live in the water, but they mostly
inhabit the banks near it; they are excellent swimmers, and may be seen
crossing lakes in shoals. America is particularly rich in them, there
are several in Europe and Asia, but they are rare in Africa, and none
have been yet discovered in Australia.
The genus Boa is peculiarly American, though some smaller in size and
differing in species are found in Asia. The boa constrictor, generally
from 9 to 15 feet long, lives in the great tropical forests of South
America, where it often watches its prey hanging from the boughs of
trees. Two of smaller size have similar habits, and two are aquatic, one
of which is sometimes 20 feet long, and another 6 feet; the latter
inhabits banks of the rivers from the Amazons to Surinam; and a species
is found at the foot of the Andes of Quito, as high as 3000 feet.
Pythons are the largest snakes of the eastern world, where they
represent the boas of the western; one species, which sometimes attains
the length of 20 feet, is spread from the western coast of Africa,
throughout intertropical Asia, to Java and China. Another, only 14 feet
long, is confined to Malacca and some of the Sunda Islands. Two others
are found only in the islands of Timor and Saparua, and one in New
Holland. There are only two species of Acrochordi, which, like boas and
pythons, twist themselves round their victims and crush them to death:
one aquatic, peculiar to Java; the other is a land snake, found
everywhere through India to New Guinea.
The West Indian islands have the snakes of North and South America, and
some peculiar; the snakes of central America are little known.
Saurians have representatives in every warm and temperate climate. The
crocodile, from its size and ferocity, claims the first place. There are
three genera of this family, all amphibious, living in rivers, or in
their estuaries: the Crocodile, properly speaking, common to the old and
new continents;[178] the Alligator or Caiman, peculiar to America; and
the Gavial, which comes nearer to the form of certain fossil crocodiles
than any other, is limited to the Ganges and other great rivers of
India. The various species of crocodiles are confined to local
habitations: three are Asiatic; two African, one of which is only in
Sierra Leone; two are peculiar to Madagascar; and in America there are
two species of crocodiles and five of alligators. The American
crocodiles inhabit the estuaries of great rivers, a species is to be met
with which ascends as high as 3000 feet at the base of the Andes of
Quito.[179]
The alligators of the Mississippi, and of the rivers and marshes of
Carolina, are more ferocious than those of South America, attacking men
and animals; they only prey in the night; while in the water, like all
their congeners, they cannot swallow their food, but they drown the
animal they have caught, hide it under water till it is putrid, and then
bring it to land to eat it. Locality has considerable influence on the
nature and habits of these animals; in one spot they are very dangerous,
while in another, at no great distance, they are cowardly. Alligators
are rarely more than 15 feet long, and are seen in large herds basking
on the banks of rivers; their cry is like the roar of a bull; in a storm
they bellow loudly, and are said to be much afraid of some of the whale
family that ascend the great American rivers. The female watches her
eggs and her young for months, never losing sight of them; but the male
devours many of them when they go into the water. All animals of this
class are covered with scales; those of the crocodile family are hard,
horny, often osseous, and impenetrable.
Lizards are chiefly distinguished from crocodiles by having a long,
thin, forked tongue like that of the viper; by their rapid motions,
smaller size, and by some peculiarities of form.
The monitors, which are entirely confined to the old continent, have the
tail compressed laterally, which enables them to swim rapidly: and they
are furnished with strong sharp teeth. Many species inhabit Africa and
India, especially the Indian Archipelago: the terrestrial crocodile of
Herodotus is common on the deserts which surround Egypt; and an aquatic
species in the Nile, which devours the crocodile’s eggs, is often
represented on the ancient Egyptian monuments.
Another group of the monitor family is peculiarly American; some of the
species inhabiting the marshes in Guiana are 6 feet long.[180]
Lizards are very common; more than 63 species are European, of which 17
inhabit Italy, and one lives on the Alps at an elevation of 4500 feet;
the iguanians, which differ from them only in the form of the tongue,
are so numerous in genera and species, that it would be in vain to
attempt to follow all their ramifications, which are nevertheless
distributed according to the same laws with other creatures: but the
dragons, only found in India, are too singular to be passed over. The
dragon is in fact a lizard with wings of skin, which are spread along
its sides and attached to its fore and hind feet, like those of the bat,
and, though they do not enable it to fly, they act like a parachute when
the animal leaps from bough to bough in pursuit of insects. Nocturnal
lizards of many species inhabit the hot countries of both continents;
they are not unlike salamanders, but they have sharp claws, which they
can draw in and conceal like those of a cat, and seize their prey. One
of this species, the Gecko, climbs on walls in all the countries round
the Mediterranean. Chameleons are frequent in northern Africa; and
several species inhabit different districts and islands in Asia: the
only European species is found in Spain; it is common to North Africa.
The anolis, which lives on trees, replaces the chameleon in the hot
regions of South America and in the Antilles, having the property common
to chameleons of changing its colour, but it is a more nimble and
beautiful animal. In New Holland, where everything is anomalous, there
is a lizard with a leaf-shaped tail.
Skinks resemble serpents in form, but with four very short feet and
sharp nails on their claws; they burrow in the sands of Africa and
Arabia: there is a species of gigantic black and yellow skink in New
Holland, and those in the islands of the Indian Archipelago are green,
with blue tails.
Two anomalous saurians of the genus Amblyrhinchus were discovered by Mr.
Darwin in the Galapagos Archipelago. One found only in the central
islands is terrestrial, and in many places it has undermined the ground
with its burrows; the other is the only lizard known that lives on
sea-weed and inhabits the sea; it is about four feet long, and hideously
ugly, with feet partially webbed, and a tail compressed laterally. It
basks on the beach, and in its marine habits and food it resembles, on a
small scale, the huge monsters of a former creation.
Tortoises are covered with a shell or buckler, but their head, legs, and
tail are free, covered with a wrinkled skin, and the animal can draw
them into the shell when alarmed. The head is sometimes defended by a
regular shield, and the jaws, instead of teeth, have a horny case. The
upper buckler is rounded, and formed of eight pairs of plates
symmetrically disposed, and often very beautiful; the under shell is
flat, and consists of four pair of bones and one in the centre. One
family of tortoises is terrestrial, two others are amphibious, one of
which lives in fresh water, the other in tropical and warm seas.
There are more land tortoises in Africa than in all the rest of the
world, both specifically and individually. They abound also in the great
Sunda Islands, in the United States of America, South America, and
especially Brazil. There are a few European species, of which the common
tortoise (Testudo Græca), which is found in all the countries round the
Mediterranean, is the largest, being about a foot long; it lives on
insects and vegetables, and burrows in the ground in winter. Some of the
East Indian species are enormously large, above three feet long, and
remarkable for the beautiful distribution of their colours; certain
species are peculiar to Brazil, one to Demerara, and one to North
America; but perhaps the largest known species is that of the Galapagos
Islands, the Testudo Indicus, which attains 500 or 600 pounds in weight.
There are two families of the fresh water tortoises that live in ponds
and ditches. The emys is very numerous in America; there are 15 species
peculiar to the northern part of the continent, and four to the
southern: only one has been found in Africa, two in Europe, and eight in
Asia. The Emys caspia, in Asia Minor, follows a leader, and plunges into
the water when alarmed. The Chelydæ are found in the South American
rivers.
The trionyx, or fresh-water turtle, lives in the great rivers and lakes
in warm countries; there are two species peculiar to North America; they
are very large and voracious, devouring birds, reptiles, and young
crocodiles, and often are a prey to old ones. One is peculiar to the
Nile, one to the Euphrates; there are four species in the Ganges, which
are constantly seen eating the bodies of the natives that are thrown
into the sacred stream; one of these turtles often weighs 240 pounds.
The starred trionyx is in the rivers of Java only, and another kind is
common also to the rivers of Borneo and Sumatra.
The Chelonians, or sea-turtles, live in the seas of the torrid and
temperate zones, to the 50th parallel of latitude, some eating algæ, and
others small marine animals. Different species are found in different
parts of the ocean. The green turtle, of which there are many varieties,
inhabits the intertropical Atlantic; they may be seen eating sea-weed at
the bottom of the water along the coasts, and they come in great shoals
to the mouths of rivers to lay their eggs in the sand from distances of
many hundred miles. This turtle is often six or seven feet long, and
weighs 600 or 700 pounds; it is much esteemed for food, but the shell is
of no value.
The hawk’s-bill turtle, which yields the tortoise-shell, is caught among
the Molucca Islands, and on the north-western coast of New Guinea. There
is also a fishery in the western hemisphere at Haiti and the Caiman
Islands, but the shell is less valuable than that from the east. There
are two species in the Mediterranean, which are only valued for the oil.
With respect to the whole class of reptiles it may be observed, that not
one species is common to the Old and New World, and few are common to
North and South America; those in New Holland are altogether peculiar;
and, as far as is at present known, with the exception of Marianne
Islands, there are neither toads, frogs, nor snakes in any of the
islands of Oceanica, though the Indian Archipelago abounds in them;
neither are they found in Tierra del Fuego, in the Straits of Magellan,
nor in the Falkland Islands.
Five species of reptiles only appear to have existed in Ireland before
its geological separation from England—a lizard, a frog, a toad, and two
tritons.