LIZARDS 693 



of both the Old and the New World, but not in Australia. In diet 

 they are vegetarian. The common tortoise {Testudo grceca) and the 

 nearly exterminated giant tortoises of the Mascarene and Galapagos 

 Islands are good representatives. The latter may reach the age of 

 150 years. 



Third Order : Lacertilia. Lizards 



General Characters. — The body is usually well covered 

 with scales. In most, both fore- and hind-limbs are developed 

 and bear clawed digits, but either pair or both pairs may be 

 absent. The pectoral and pelvic girdles are always present, 

 in rudiment at least. There is a sternum and a J -shaped 

 episternum. Unlike snakes, lizards have non- expansible 

 mouths. The maxillce, palatines, and pterygoids are fixed, 

 and there is usually a mandibular symphysis. There are 

 almost always movable eyelids and external ear-openings. 

 The teeth are fused to the edge or to the ridge of the jaws, never 

 planted in sockets. The tongue, broad and short in some, 

 e.g. Geckos and Iguanas, long and terminally clubbed 

 in Chamceleons, is oftenest a narrow bifid organ of touch. 

 The opening of the cloaca is transverse. There is a urinary 

 bladder, corresponding to that of the frog, and a double penis. 

 Most are oviparous, but in a few the eggs are hatched zvithin 

 the body. They are usually active, agile animals, beautifully 

 and often protectively coloured. The tail is readily thrown 

 off by a reflex action ; lost tails a?id even legs may be re- 

 generated. The food generally consists of insects, worms, 

 and other small animals, but some prey upon larger animals, 

 and others are vegetarian. Most are terrestrial, some 

 arboreal, a few semi-aquatic, and there is one marine form. 

 Lizards are most abundant in the Tropics, and are absent 

 from very cold regions. 



Description of a Lizard as a ^Type of Reptiles 



The following description appUes especially to the long- 

 tailed green lizard {Lacerta viridis), found abundantly in 

 Jersey, but, except in minor points, it will be found to apply 

 equally to the small British grey lizard {Lacerta agilis) and 

 to the viviparous lizard {Lacerta vivipara) : — 



Form and external features. — The depressed head is 

 separated from the body by a distinct neck, but the 



