THE LIZARDS 2467 



America. As has already been noticed, the distribution of tortoises approximates 

 to the former type, all the Side-necked group being confined to the Southern Hemi- 

 sphere. Again, we find that whereas tropical Africa is closely related to tropical 

 India as regards its Amphibians, while Australia and Africa are near akin to South 

 America in regard to their tortoises, in respect of lizards there is no close connection 

 between India and Africa, but an intimate relationship exists between India and 

 Australia, where members of the same genera occur; while the Australian lizards 

 are totally unlike their South- American cousins. As might have been expected 

 from their great numerical preponderance at the present day, lizards appear to be a 

 comparatively-modern group, their remains being rare in the lower Tertiary depos- 

 its, while in the Secondary period they are only known by a few species from the 

 rocks of the Cretaceous epoch. That the group has originated from the tuateras, 

 which were so abundant in the earlier strata of the Secondary period, may be regarded 

 as most probable. 



Turning to their mode of life, we find that while a few members of 

 the order resemble crocodiles, in spending the greater portion of their 

 time in water, visiting the land o*ily for the purposes of feeding, sleeping, or basking 

 in the sun, by far the greater majority of lizards are essentially land animals, avoid- 

 ing even damp situations. Although some inhabit trees, the greater number dwell 

 either on the ground or among the clefts of rocks, the conformation of the body 

 generally giving some indication of this diversity of habitat. ' Among the land forms, 

 for instance, those with depressed bodies are generally to be found in open sandy 

 deserts, where they seek shelter either beneath stones or in holes; whereas such as 

 have the body compressed are more usually dwellers among bushes or in trees. 

 Those, again, in which the body is more or less cylindrical, are in the habit of se- 

 creting themselves in the clefts of rocks or the chinks of tree stems; while the snake- 

 like kinds live on the ground, and those with a more worm-like form beneath the 

 surface. The movements of the greater number of species whether they live on 

 the ground, among rocks, on trees, or on cliffs or walls are agile in the extreme; 

 and while the majority run with their bodies close to the ground, many habitually 

 raise themselves up at times by resting on their hind-legs and tails, and are able to 

 spring, either on the ground or from branch to branch, to a considerable distance 

 after their prey. Of the arboreal species, some make use of their tails to aid in 

 maintaining their hold, while others, together with cliff- and wall-hunting species, 

 like the geckoes, are enabled to run along the under sides of boughs, or to ascend 

 vertical surfaces by the aid of their expanded and disc-like feet. The peculiar fly- 

 ing lizard is enabled to take long, flying leaps, supported by a parachute-like mem- 

 brane borne by the expanded ribs; while all the limbless species move somewhat 

 after the manner of snakes, although making less use of the extremities of the ribs. 

 The few aquatic forms swim and dive without the aid of webbed feet, but many 

 other kinds swim well if thrown into water. 



In many cases elegant and graceful in form, although at others rendered more 

 curious than beautiful by the presence of spines or warts, lizards are pleasing rather 

 than repulsive animals; and, with the exception of the American heloderms, none 

 are poisonous, although some will bite sharply. Few lizards possess a distinct 



