Lizards
Of the two groups of the Squamata, the lizards are of course the older. They have the conventional body plan of a typical land vertebrate: four legs, five toes to a foot, and the sprawling gait of the earliest reptiles. Most of the adaptations that have allowed them to spread and prosper are relatively unspectacular changes in the old four-legged look-exceptions being the various groups in which the legs have been lost completely.
In spite of their fundamentally conventional body plan, modern lizards are a diverse lot. They range in length from two inches to 10 feet. They may look like dragons and they may look like worms, and they show a complex adaptive range through terrestrial, arboreal, subterranean and aquatic environments. The large family of the Iguanidae, represented by the slender anole that stalks insects on the screens, and by the scaly-backed fence lizards that bask on almost every log or stump. This is, as the name suggests, the group to which the big tropical arbreal and marine iguanas belong, and it includes a host of smaller forms. The family Agamidae, which has a curiously similar structural and ecological spread, represents it in Europe.
The classic lizards-classic because they are of the Old World and since early times have beguiled European naturalists-are the personable lacertas of the family Lacertidae. There is another family of lizards called Teiidae. The teiids are an alert and active group of lizards that occur mostly in South America but are also found foaging among chickens and babies in villages throughout the Caribbean.
The most cosmopolitan lizard family is that of the skinks, the Scincidae (shiny-scaled lizard) with protrusible tongues and a generally surreptitious air, which may account for their being occasionally known as scorpions. One of the farm skinks, the ground lizard, is a brown creature not much bigger than a wooden matchstick. The other is the big, burnished red-headed "scorpion", which confuses squirrel hunters with the noise it makes running up the trunks of trees.
We also have two kinds of lizards that have no legs. One is the so-called glass snake, which dashes headlong into the soil and makes one wonder why a British relative is known as the slow-worm. The other is the Florida worm lizard, a blind, pink, double-ended creature like a blunt lob worm. The worm-lizard family is called Amphisbaenidae, literally meaning, "to walk on both ends", because among most of the creatures in it both ends look surprisingly alike. As these two burrowers show, snakes were not the only legless descendants of the ancestral lizard stocks. Through the world list of lizard families, legless members repeatedly turn up, a drastic adaptation that seems odd o a beast as dependent on his legs as man.
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