422 Vertehrata. 



1. Lizards (Lacerta) liave a long round tail; well- developed limbs; smaU. 

 dorsal scales, larger ones ventrally, usually an'anged in longitudinal rows ; 

 tongue well-developed and bifid. In England, the two very similar species, the 

 Sa n d L i z a ]■ d (i. agilis) and the C o m m o n L i z a r d (£. vivipara) are abundant- 

 Allied are the Varanids (Varanus), large, ti-opical, old-world forms with 

 long bifid tongue. 



2. Iguanas (Iguanidse), Lacertilia with small scales; and a thick, slightly- 

 bifid tongue ; many have spines, ridges, and so forth on the skin. They fall 

 into two natural gi-oups, belonging to the Old and the New "World ; the fonner 

 aorodont (?.e., with teeth fused to the edge of the jaw), the latter pleuro- 

 d o n t (teeth on the inner side of the jaw. Fig. 281) . Within both gi-oups, there are 

 elongate, long-legged, long- tailed forms (Tree Iguanas), and bulky, flat, 

 short-tailed foi'ms (Ground Iguanas); between these, there is no sharp 

 distinction, as there are many inteimediate fonns. A peculiar genus of 

 small tree Iguanas, the Plying Lizards or Dragons (Draco volans), 

 have the false ribs not in the body-wall, but lying tm-ned outwards, to form on 

 either side supports for a large fold of the skin, which acts as a patagium. 

 East Indies. 



3. The Blind-worm (Anguis fragilis), an apodous Lizard, with long tail 

 and movable eyelids ; viviparous ; abundant in England. It belongs to the 

 family of the Skinks (Scincoidei), which are characterised by smooth, flattened 

 scales, and a short, flat tongue ; within this family, thei-e are forms with well- 

 developed limbs, aiid a relatively short body ; forms with more or less degenerate 

 limbs and a longer body ; and lastly, apodous species like the Blind-worm. The 

 other species belong to wanner countries ; some occuiTing on the coasts of the 

 Mediterranean. 



4. Chameleons (Chamasleo) constitute a very peculiar gi-oup of Lizai-ds. 

 The slit between the eyelids is very narrow, the latter almost entu-ely cover the eye- 

 ball, to which they are attached, and with which they move ; the tongue, which 

 can be withdrawn into a sheath, is club-Uke, of considerable length, and can be 

 projected some way from the mouth ; the fingers or toes of each foot have gi-own 

 together into two bundles, each consistuig of two or three digits, which are united 

 almost to the tip, but separated from the other bundle down to the tarsus ; the 

 two bundles are s.' turned that they work together like the limbs of a 

 pair of tongs, and may be used for seizing branches ; body compi-essed ; tail 

 cm-led up ; scales very small ; the power of the Chameleons to change their 

 colour is very well known : in warmer countries (especially Africa) ; one species 

 in Andalusia. 



5. The Geckos lAscalahotse) are characterised by the presence of suckei-s 

 on the lower side of the toes, and of eyelids like those of Snakes (see p. 415) ; 

 usually flattened animals, with compressed scales ; in warm countries (even in 

 S. Eui-ope). 



6. Ringed Lizards (genus Amphishsena, etc.), short-tailed, elongate, 

 cylindrical fonns, with very small eyes ; usually apodous (or with only small 

 fore limbs) ; scales quadi-angular, not imbricating, an-anged in transverse rings ; 

 mode of life like that of the Ocecilias ; in warm countries (one species in 

 S. Eiu'ope). 



Order 2. OpMdia. (Snakes.) 



SnakeSj which are nearly related to Lizard Sj are characterised by 

 the absence of limbs (occasionally there are rudiments of the hind 

 ones) J the structure of the eyelids already mentioned (p. 415) ; 



