94 SAURIA. IGUANAD^. 



bercles, often ridged or spinous, always horny in 

 texture, not bony : those of the head frequently 

 take the form of many-sided plates, more or less 

 large, and those of the belly are square and over- 

 lapping. The scales of the back are generally 

 elevated into spinous processes, forming a saw- 

 like crest, which runs down the back and tail in 

 various degrees. The toes are always free, com- 

 monly slender ; but in some genera, as Anolis, 

 Dactyloa, &c., they have the dilated and lamel- 

 lated tips of the Gechotidcs. These have the 

 power of crawling with ease and rapidity on per- 

 pendicular surfaces, and haunt out-buildings, and 

 even dwelling-houses in the hot parts of America 

 and the West Indies, running with great agility 

 about the walls, and leaping from place to place ; 

 while others run and leap with equal spright- 

 liness among the twigs and leaves of low shrubs 

 in pursuit of insects. These have the faculty of 

 changing their colours, which is eifected with a 

 rapidity and to an extent scarcely inferior to 

 what we see in the Chameleons. All the genera 

 appear to be more or less arboreal ; the larger 

 species, or true Iguanas, living almost entirely 

 on trees : these are reported to be able to swim 

 with ease, but their feet do not manifest any 

 structural adaptation to aquatic habits, and we 

 doubt whether they ever take to the water ex- 

 cept in an emergency, or impelled by some un- 

 usual motive. 



Most of the species in this Family have some 

 expansion of loose skin about the neck. In the 

 Iguanas it hangs down in a permanent sort of 

 dewlap, but in the Anoles it is ordinarily con- 

 tracted and consequently invisible, but is ex- 



