reptilia 551 



Order Squamata 



Suborder Lacertilia (Sauria) (The Lizards). — This group contains 

 more different kinds of living animals than any other suborder 

 among the reptiles. There are more than 2,500 living species known 

 on earth. Of this number, about 175 species are found in North 

 America, north of Mexico. Kepresentatives of nine families are 

 found among them. 



Family GekJconidae. — There are about fifty genera, containing 

 some 300 species, in this family. They are found around the world 

 in the tropical and semitropical regions. Seven species are known 

 from the United States and neighboring regions. 



All of our species are small, seldom attaining a length of six 

 inches; but some tropical forms may be over a foot in length. The 

 colors vary considerably but are often bright, as is usual in noctur- 

 nal animals. The scales of the skin are very minute. This gives 

 the geckos a soft, smooth, appearance unlike that of any of the 

 other lizards. The eyes usually have vertical pupils and are with- 

 out lids, though they are covered by a transparent, cutaneous mem- 

 brane. As in some other lizards, there is nothing obstructing the 

 auditory passage through the head. It is possible to see through 

 this passage. Members of this family are among the few lizards 

 that can make a sound other than hissing. Their characteristic 

 call sounds like the word "gecko." 



In a great many species the toes are flattened on the end to form 

 adhesive discs. These enable a gecko to walk across the ceiling of 

 a room with ease. In most species the tail is short and thick. 



Geckos sleep during the day but come forth at nightfall in search 

 of their insect prey, which they capture by means of their short 

 sticky tongues. 



Family Iguanidae. — This family of lizards has more representa- 

 tives in the United States than any other single family. Of ap- 

 proximately 175 species of lizards known from this country, 90 

 species and 19 subspecies belong to this family. Representatives 

 are found in all parts of the United States except the most northern 

 portion, as well as throughout Central and South America, and the 

 West Indies. Two genera are found in Madagascar and one in the 

 Fiji Islands. As might be expected in so large a group, great varia- 



