are usually differentiated into incisors, canines and molars. The skin
is devoid of ossifications, but large and numerous cutaneous spines
are often present, especially on the head and on the tail. The family,
comprising some 200 species, with about 30 genera, shows great
diversity of form; the terrestrial members are mostly flat-bodied, the
arboreal more laterally compressed and often with a very long tail.
Most of them are insectivorous, but a few are almost entirely
vegetable feeders. They are an exclusively Old World family; they are
most numerous in Australia (except New Zealand) and the Indian and
Malay countries; comparatively few live in Africa (none in Madagascar)
and in the countries from Asia Minor to India.
The majority of the ground-agamas, and the most common species of the
plains, deserts or rocky districts of Africa and Asia, belong to the
genera _Stellio_ and _Agama_. Their scales are mixed with larger
prominent spines, which in some species are particularly developed on
the tail, and disposed in whorls. Nearly all travellers in the north
of Africa mention the _Hardhón_ of the Arabs (_Agama stellio_), which
is extremely common, and has drawn upon itself the hatred of the
Mahommedans by its habit of nodding its head, which they interpret as
a mockery of their own movements whilst engaged in prayer. In some of
the Grecian islands they are still called _korkordilos_, just as they
were in the time of Herodotus. _Uromastix_ is one of the largest of
ground-agamas, and likewise found in Africa and Asia. The body is
uniformly covered with granular scales, whilst the short, strong tail
is armed with powerful spines disposed in whorls. The Indian species
(_U. hardwicki_) is mainly herbivorous; the African _U. acanthinurus_
and _U. spinipes_, the Dab of the Arabs, take mixed food.
_Phrynocephalus_ is typical of the steppes and deserts of Asia.
_Ceratophora_ and _Lyriocephalus_ scutatus, the latter remarkable for
its chameleon-like appearance, are Ceylonese. _Calotes_, peculiar to
Indian countries, comprises many species, e.g. _C. ophiomachus_,
generally known as the "bloodsucker" on account of the red colour on
the head and neck displayed during excitement. _Draco_ (see DRAGON) is
Indo-Malayan. _Physignathus_ is known from Australia to Cochin China.
Of the Australian agamas no other genus is so numerously represented
and widely distributed as _Grammatophora_, the species of which grow
to a length of from 8 to 18 in. Their scales are generally rough and
spinous; but otherwise they possess no strikingly distinguishing
peculiarity, unless the loose skin of their throat, which is
transversely folded and capable of inflation, be regarded as such. On
the other hand, two other Australian agamoids have attained some
celebrity by their grotesque appearance, due to the extraordinary
development of their integuments. One (fig. 1) is the frilled lizard
(_Chlamydosaurus kingi_), which is restricted to Queensland and the
north coast, and grows to a length of 3 ft., including the long
tapering tail. It is provided with a frill-like fold of the skin round
the neck, which, when erected, resembles a broad collar. This lizard
when startled rises with the fore-legs off the ground and squats and
runs on its hind-legs. The other lizard is one which most
appropriately has been called _Moloch horridus_. It is covered with
large and small spine-bearing tubercules; the head is small and the
tail short. It is sluggish in its movements, and so harmless that its
armature and (to a casual observer) repulsive appearance are its sole
means of defence. It grows only to a length of 10 in., and is not
uncommon in the flats of South and West Australia.
Family 2. _Iguanidae._--Pleurodont; tongue broad and thick, not
protractile; no osteoderms. America, Madagascar and Fiji Islands.
According to the very varied habits, their external appearance varies
within wide limits, there being amongst the 300 species, with 50
genera, arboreal, terrestrial, burrowing and semi-aquatic forms, and
even one semi-marine kind. All have well-developed limbs. In their
general structure the _Iguanidae_ closely resemble the _Agamidae_,
from which they differ mainly by the pleurodont dentition. Most of
them are insectivorous. Some, especially _Anolis_ and _Polychrus_, can
change colour to a remarkable extent. The family ranges all through
the neotropical region, inclusive of the Galapagos and the Antilles,
into the southern and western states of North America. Remarkable
cases of discontinuous distribution are _Chalarodon_ and _Hoplodon_ in
Madagascar, and _Brachylophus fasciatus_ in the Fiji Islands.
_Conolophus subcristatus_ and _Amblyrhynchus cristatus_ inhabit the
Galapagos; the former feeds upon cactus and leaves, the latter is
semi-marine, diving for the algae which grow below tide-marks. For
_Basiliscus_ see BASILISK; IGUANA is dealt with under its own heading;
allied is _Metopoceros cornutus_ of Hayti. _Polychrus_, the
"chameleon," and _Liolaemus_ are South American; _Ctenosaura_ of
Central America and Mexico resembles the agamoid _Uromastix_.
_Corythophanes_ and _Laemanctus_, with only a few species, are rare
inhabitants of the tropical forests of Central America and Mexico.
_Sauromalus_, _Crotaphytus_, _Callisaurus_, _Holbrookia_, _Uma_, _Uta_
are typical Sonoran genera, some ranging from Oregon through Mexico.
Allied is _Sceloporus_, with about 34 species, the most characteristic
genus of Mexican lizards; only 4 species live in the United States,
and only 3 or 4 are found south of the Isthmus of Tehuantepec and are
restricted to Central America. The majority are humivagous, while
others are truly arboreal, e.g. _S. microlepidotus_, a species which,
moreover, has the greatest possible altitudinal range, from the hot
country of southern Oaxaca to the upper tree-line of Citlaltepetl,
about 13,500 ft. elevation; many species are viviparous. _Phrynosoma_,
with about a dozen species, the "horned toads" of California to Texas,
and through Mexico. Some of these comical-looking little creatures are
viviparous, others deposit their eggs in the ground. They are well
concealed by the colour of their upper parts, which in most cases
agrees with the prevailing tone of their surroundings, mostly arid,
stony or sandy localities; the large spikes on the head protect them
from being swallowed by snakes. The enlarged spiny scales scattered
over the back look as if it were sprinkled with the dried husks of
seeds. They are entirely insectivorous, bask on the broiling hot sand
and then can run fast enough; otherwise they are sluggish, dig
themselves into the sand by a peculiar shuffling motion of the fringed
edges of their flattened bodies, and when surprised they feign death.
The statement, persistently repeated (O. P. Hay, _Proc. U.S. Nat.
Mus._ xv., 1892, pp. 375-378), that some, e.g. _P. blainvillei_ of
California, have the power of squirting a blood-red fluid from the
corner of the eye, still requires renewed investigation.
[Illustration: FIG. 1.--Frilled Lizard (_Chlamydosaurus kingi_).]
The smallest lizards of this family belong to the genus _Anolis_,
extremely numerous as regards species (more than 100) and individuals
on bushes and trees of tropical America, and especially of the West
Indies. They offer many points of analogy to the humming birds in
their distribution, colours and even disposition. Hundreds may be seen
on a bright day, disporting themselves on trees and fences, and
entering houses. Like the iguanas, they (at least the males) are
provided with a large, expansible dewlap at the throat, which is
brilliantly coloured, and which they display on the slightest
provocation. This appendage is merely a fold of the skin, ornamental
and sexual; it has no cavity in its interior, and has no communication
with the mouth or with the respiratory organs; it is supported by the
posterior horns of the hyoid bone, and can be erected and spread at
the will of the animal. The presence of such dewlaps in lizards is
always a sign of an excitable temper. Many, e.g. _A. carolinensis_,
the "chameleon," can change colour to an extraordinary degree. They
are much fed upon by birds and snakes, and have a fragile tail, easily
reproduced. They bring forth only one large egg at a time, but
probably breed several times during the season.
Family 3. _Xenosauridae._--Pleurodont; solid teeth; anterior part of
tongue slightly emarginate and retractile, and covered with flat
papillae; no osteoderms. Mexico.
The only representative of this family is _Xenosaurus grandis_,
recorded from the mountains of Orizaba, Cordoba and Oaxaca. The
four-footed creature is less than 1 ft. in length; the body is
depressed, covered above with minute granules and tubercles; a
distinct fold of skin extends from the axilla to the groin, reminding
of the similar fold of some _Anguidae_, to which this singular genus
seems to be allied.
Family 4. _Anguidae._--Pleurodont; teeth solid, sometimes
(_Ophiosaurus_) grooved; anterior part of tongue emarginate and
retractile into the posterior portion; osteoderms on the body, and
especially on the head where they are roofing over the temporal fossa;
entirely zoophagous and ovo-viviparous. America, Europe and India.
_Gerrhonotus_, 8 species, in mountainous countries, from British
Columbia to Costa Rica; like _Diploglossus s. Celestus_ of Mexico, the
Antilles and Central America, with well-developed limbs, but with a
lateral fold. _Anguis fragilis_ and two species of _Ophiosaurus_ are
the only members of this family which are not American, and even the
third species of _Ophiosaurus_, _O. ventralis_, lives in the United
States. _Ophiosaurus s. Pseudopus_, the glass-snake, from Morocco and
the Balkan peninsula to Burma and Fokien; also in the U.S.A., with the
limbs reduced to a pair of tiny spikes near the vent, and a lateral
fold along the snake-like body. _Anguis_, with its sole species
fragilis, the slow-worm or blind-worm, is devoid of a lateral fold,
and the limbs are entirely absent. Europe, Algeria and western Asia.
Family 5. _Helodermatidae_, with _Heloderma_ of Arizona and Mexico,
and _Lanthanotus_ of Borneo.--The teeth of _Heloderma_ are recurved,
with slightly swollen bases, loosely attached to the inner edge of the
jaws; each tooth is grooved, and those of the lower jaw are in close
vicinity of the series of labial glands which secrete a poison; the
only instance among lizards.[2] Limbs well developed. Tongue
resembling that of the _Anguidae_. The skin of the upper surface is
granular, with many irregular bony tubercles which give it an ugly
warty look. _H. horridum_ in Mexico, and _H. suspectum_, the gila
monster, in the hot and sandy lowlands of the Gila basin. The animal,
which reaches a length of more than 2 ft., is blackish-brown and
yellow or orange, and on the thick tail these "warning colours" are
arranged in alternate rings. Small animals are probably paralyzed or
killed by the bite, the poison being effective enough to produce
severe symptoms even in man. The Zapotecs, who call the creature
Talachini, and other tribes of Mexico have endowed it with fabulous
properties and fear it more than the most poisonous snakes.
_Lanthanotus corneensis_, of which only a few specimens are known, is
apparently closely allied to _Heloderma_, although the teeth are not
grooved, osteoderms are absent and probably also the poison glands.
Family 6. _Aniellidae._--One genus, _Aniella_, with a few worm- or
snake-shaped species in California, which seem to be degraded forms of
_Anguidae_. The eyes and ears are concealed, the limbs are entirely
absent, body and tail covered with soft, imbricating scales. The
tongue is villose, smooth, bifid anteriorly. The few teeth are
recurved, with swollen bases. The skull is much reduced. Total length
of _A. pulchra_ up to 8 in.
Family 7. _Zonuridae._--Pleurodont; tongue short, villose, scarcely
protractile, feebly nicked at the tip. With osteoderms at least upon
the skull, where they roof in the temporal region. Africa and
Madagascar.
Only 4 genera, with about 15 species. _Zonurus_ of South Africa and
Madagascar has the whole head, neck, back and tail covered with strong
bony scales, the horny covering of which forms sharp spikes,
especially on the tail. They defend themselves by jerking head and
tail sidewards. _Z. giganteus_ reaches 15 in. in length, and is, like
the other members of the family, zoophagous. The other genera live in
southern and in tropical Africa: _Pseudocordylus_, _Platysaurus_ and
_Chamaesaura_; the latter closely approaches the _Anguidae_ by its
snake-shaped body, very long tail and much reduced limbs, which in _C.
macrolepis_ are altogether absent.
Family 8. _Xantusiidae._--Pleurodont; tongue very short and scaly; no
osteoderms; supratemporal fossa roofed over by the cranial bones; eyes
devoid of movable lids; tympanum exposed; femoral pores present; limbs
and tail well developed. American.
_Xantusia_ (so named after Xantus, a Hungarian collector), e.g. _X.
vigilis_ and a few other species from the desert tracts of Nevada and
California to Lower California. _Lepidophyma flavomaculatum_, Central
America; and _Cricosaura typica_ in Cuba.
Family 9. _Tejidae._--Teeth solid, almost acrodont; tongue long and
narrow, deeply bifid, beset with papillae; no osteoderms; scales of
the back very small or quite granular; limbs sometimes reduced.
America.
This large, typically American family comprises more than 100 species
which have been arranged in many genera. Some are entirely arboreal,
dwellers in forests, while others, like _Cnemidophorus_ and _Ameiva_,
are strictly terrestrial, with great running powers; a few dwell below
the surface and are transformed into almost limbless worm-shaped
creatures. The family is essentially neotropical. Of its several dozen
genera only two extend through and beyond Central America: _Ameiva_
into the eastern and western Hot-lands of Mexico, _Cnemidophorus_
(monographed by H. Gadow, _Proc. Zool. Soc._, 1906, pp. 277-375)
through Mexico into the United States, where _C. sexlineatus_, the
"swift," has spread over most of the Union. _Tupinambis teguixin_, the
"teju" of South America and the West Indies, is the largest member of
the family; it reaches a length of a yard, most of which, however,
belongs to the strong, whip-like tail. _Teguixin_ is taken from the
Aztec _teco-ixin_, i.e. rock-lizard, the vernacular name of
_Sceloporus torquatus_ which is one of the _Iguanidae_ misspelt and
misapplied. The tejus frequent forests and plantations and are
carnivorous, eating anything they can overpower. They in turn are much
hunted for the sake of their delicate flesh. They defend themselves
not only with their powerful jaws and sharp claws, but also with
lashing strokes of the long tail. They also use this whip for killing
snakes which they are said to eat. Their long-oval, hard-shelled eggs
are deposited in the ground. They retire into self-dug burrows.
_Cophias_ and _Scolecosaurus_ have very much reduced limbs. In the
genus _Tejus_ the teeth of the adult become molar-like; and in
_Dracaena_ they are transformed into large, oval crushers, indicating
strictly herbivorous habits, while most members of the family live
upon animal food.
Family 10. _Amphisbaenidae._--The body is covered with soft skin,
forming numerous rings with mere vestiges of scales. Worm-shaped,
without limbs, except _Chirotes_ which has short, clawed fore-limbs.
Eyes and ears concealed. Tongue slightly elongated, covered with
scale-like papillae and bifurcating. Tail extremely short. Acrodont or
pleurodont. America, Mediterranean countries, and Africa with the
exception of Madagascar.
_Chirotes canaliculatus_, and two other species; Pacific side of
Mexico and Lower California. With five, four or three claws on the
stout little digging fore-limbs. These pink, worm-like creatures live
in sandy, moist localities, burrowing little tunnels and never
appearing on the surface. _Amphisbaena_ (q.v.). _Rhinëura_ of Florida,
and also known from the Oligocene of South Dakota; _Lepidosternum_ of
South America; and _Anops_ in America and Africa; _Blanus cinereus_,
Mediterranean countries. _Trogonophis_, _Pachycalamus_ and _Agamodon_
of Africa are all acrodont; the other genera are pleurodont. In all
about a dozen genera, with some 60, mostly tropical species.
Family 11. _Scincidae._--Pleurodont. Tongue scaly, feebly nicked in
front. Osteoderms on the head and body. Limbs often reduced.
Cosmopolitan. The temporal region is covered over, as in the
_Lacertidae_ and _Anguidae_, with strongly developed dermal
ossifications. Similar osteoderms underlie the scales of the body and
tail. Femoral pores are absent.
All the skinks seem to be viviparous, and they prefer dry, sandy
ground, in which they burrow and move quickly about in search of their
animal food. This partly subterranean life is correlated with the
frequent reduction of the limbs which, in closely allied forms, show
every stage from fully developed, five-clawed limbs to complete
absence. Some have functional fore-limbs but mere vestiges of
hind-limbs; in others this condition is reversed. In some
deserticolous kinds e.g. _Ablepharus_, the lower eyelid is transformed
into a transparent cover which is fused with the rim of the reduced
upper lid. The same applies to the limbless little _Ophiopsiseps
nasutus_ of Australia. This large family contains about 400 species,
with numerous genera; the greatest diversity in numbers and forms
occurs in the tropical parts of the Old World, especially in the
Australian region, inclusive of many of the Pacific islands. New
Zealand has at least 6 species of _Lygosoma_. America, notably South
America, has comparatively very few skinks.
The skink, which has given the name to the whole family, is a small
lizard (_Scincus officinalis_) of 6 or 8 in. in length, common in arid
districts of North Africa and Syria. A peculiarly wedge-shaped snout,
and toes provided with strong fringes, enable this animal to burrow
rapidly in and under the sand of the desert. In former times large
quantities of it were imported in a dry state into Europe for
officinal purposes, the drug having the reputation of being
efficacious in diseases of the skin and lungs; and even now it may be
found in apothecaries' shops in the south of Europe, country people
regarding it as a powerful aphrodisiac for cattle.
_Mabouia_, with many species, in the whole of Africa, southern Asia
and in tropical America. _M. (Euprepes) vittata_, the "poisson de
sable" of Algeria, is semi-aquatic. _Chalcides s. Seps_, of the
Mediterranean countries and south-western Asia, has a transparent disk
on the lower eyelid which is movable; limbs very short or reduced to
mere vestiges. _Lygosoma_ circumtropical; _Eumeces_, also with many
small species, in America, Africa and Asia. _Cyclodus s. Tiliqua_ of
Australia, Tasmania and Malay Islands, has stout lateral teeth with
rounded-off crowns; _C. gigas_ of the Moluccas and of New Guinea is
the largest member of the family, reaching a length of nearly 2 ft.;
the limbs are well developed, as in _Trachysaurus rugosus_ of
Australia, which is easily recognized by the large and rough scales
and the short, broad, stump-like tail.
Family 12. _Anelytropidae._--An artificial assembly of a few degraded
Scincoids. The worm-shaped body is devoid of osteoderms. The tongue is
short, covered with imbricating papillae and slightly nicked
anteriorly. Teeth pleurodont. _Anelytropsis papillosus_, of which only
three specimens are known, from the humus of forests in the state of
Vera Cruz. Eyes concealed. _Typhlosaurus_ and _Feylinia_ in tropical
Africa and Madagascar.
Family 13. _Dibamidae._--_Dibamus novae-Guineae_ of New Guinea, the
Moluccas, Celebes and the Nicobar Islands. Tongue arrow-shaped,
covered with curved papillae. The vermiform body is covered with
cycloid imbricating scales, devoid of osteoderms. Limbs and even their
arches are absent, excepting a pair of flaps which represent the
hind-limbs in the males.
Family 14. _Gerrhosauridae._--Pleurodont. Tongue long, with papillae,
like that of the _Lacertidae_ but only feebly nicked anteriorly.
Osteoderms on the head and body, roofing over the temporal region.
Femoral pores present, also mostly a lateral fold. Limbs sometimes
reduced to small stumps. Tail long and brittle. The few genera and
species of this family are restricted to Africa, south of the Sahara
and Madagascar.
_Gerrhosaurus_, with lateral fold and complete limbs; _Tetradactylus_
also with a fold, but with very variable limbs; _Condylosaurus_; all
in Africa. _Zonosaurus_ and _Tracheloptychus_ in Madagascar.
Family 15. _Lacertidae._--Pleurodont. Tongue long and bifid, with
papillae or folds, with osteoderms on the head but not on the body.
Limbs always well developed. Palaearctic and palaeotropical with the
exception of Madagascar; not in the Australian region.
The _Lacertidae_ or true lizards comprise about 20 genera, with some
100 species, most abundant in Africa; their northern limit coincides
fairly with that of the permanently frozen subsoil. They all are
terrestrial and zoophagous. The long, pointed tail is brittle.
[Illustration: FIG. 2.--Heads of British Lizards. a, _Lacerta
vivipara_; b, _L. agilis_; c, _L. viridis_.]
Most of the European lizards with four well developed limbs belong to
the genus _Lacerta_. Only three species occur in Great Britain (see
fig. 2). The common lizard (_Lacerta vivipara_) frequents heaths and
banks in England and Scotland, and is locally met with also in
Ireland; it is viviparous. Much scarcer is the second species, the
sand-lizard (_Lacerta agilis_), which is confined to some localities
in the south of England, the New Forest and its vicinity; it does not
appear to attain on English soil the same size as on the continent of
Europe where it abounds, growing sometimes to a length of 9 in.
Singularly, a snake (_Coronella laevis_), also common on the
continent, and feeding principally on this lizard, has followed it
across the British Channel, apparently existing in those localities
only in which the sand-lizard has settled. This lizard is oviparous.
The males differ by their brighter green ground colour from the
females, which are brown, spotted with black. The third British
species, the green lizard (_Lacerta viridis_), does not occur in
England proper; it has found a congenial home in the island of
Guernsey, but is there much less developed as regards size and beauty
than on the continent. This species is larger than the two preceding;
it is green, with minute blackish spots. In Germany and France one
other species only (_Lacerta muralis_) appears; but in the south of
Europe the species of _Lacerta_ are much more numerous, the largest
and finest, being _L. ocellata_, which grows to a length of 18 or 20
in., and is brilliantly green, ornamented with blue eye-like spots on
the sides. Even the small island-rocks of the Mediterranean, sometimes
only a few hundred yards in diameter, are occupied by peculiar races
of lizards, which have attracted much attention from the fact that
they have assumed under such isolated conditions a more or less dark,
almost black, coloration. _L. muralis_, with its numerous varieties,
has been monographed by G. A. Boulenger, _Trans. Zool. Soc._ xvii.
(1905), pp. 351-422, pl. 22-29.
Other genera are _Psammodromus_ and _Acanthodactylus_ in south-western
Europe and northern Africa. _Cabrita_ in India, with transparent lower
eyelids. _Ophiops_, likewise with transparent but united lids, from
North Africa to India.