_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.