LIZARDS 
Lizards are the most abundant of the living reptiles, comprising twenty-one 
families, divided into more than twenty-five hundred species. As a rule, 
they are coated with scale-like folds of the skin, have four legs and a 
tapering tail. Some, however, are legless and resemble snakes, but even 
these can be distinguished by their ear openings and movable eyelids. 
Lizards vary considerably in size, ranging from the ten-foot-long 
dragon of Komodo Island to the tiny tropical American gecko, less than 
two inches in length and weighing all of one-fifth of an ounce. 
Simplified, the chief groups of lizards may be arranged as follows: 
Geckos , of which there are more than two hundred and seventy-five 
species, are egg-laying, soft-skinned small lizards found in almost all tem¬ 
perate and tropical countries. Included with them are four species of large¬ 
eyed uroplatids from Madagascar whose lichen-like skins resemble the 
tree trunks to which they cling; five species of xantusids, inhabiting the 
western deserts of North America and the arid regions of Central America 
and Cuba; three species of serpent-like Malayan dibambids, in which the 
hind limbs of the females are lacking and those of the males are so 
degenerated that they probably are used only as claspers; five species of 
limbless burrowing feylinids of Madagascar and Africa, whose eyes are 
completely covered by skin; and the single anelytropsid, resembling a 
feylinid, which is found only in the humus of certain Mexican forests. 
Skinks are medium-sized lizards of cosmopolitan distribution covered 
with overlapping scales, beneath each of which is a bony plate embedded 
in the skin. Studies by Taylor, Burt and others indicate that the family is 
on the ascendant. In this grouping of approximately four hundred species 
are included the gerrhosaurids, a small family of about fifteen species 
confined in range to Africa and Madagascar. 
Old and New World Lizards include the lacertids and teiids. The 
ninety-odd species of lacertids inhabit all parts of the Eastern Hemisphere 
with the exception of Madagascar and the Australian region, while the 
one hundred and twenty-five species of teiids, which superficially resemble 
them, are generally confined to the American tropics. 
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