178 REPTILES OF THE WORLD 



One of the most pronounced examples of specialization 

 involves the eyes of some species that live in sandy places 

 and burrow to a considerable extent. This consists of 

 a transparent disk in the lower eyelid, so that the eye 

 may be protected while the animal is digging, yet the 

 organ may be of use at the same time. This character 

 will be found with the genera Eremias and Cabrita, 

 of Africa and India. The species of Ophiops ( Snake- 

 Eyed Lizards), a genus represented by six species in 

 northern Africa, southwestern Asia and in India, show 

 this character carried to an extreme. The eye is perma- 

 nently open and covered with a transparent disk like the 

 eye of a snake, though both eyelids are present. Spe- 

 cialization has been carried forward until the disk in the 

 lower eyelid — seen with Eremias,, and notably large with 

 Cabrita — has overspread the eye, while the lower lid has 

 fused with the upper. The species so provided live in 

 dry, sandy places and burrow with wonderful agility. 



Like the Teii&ce, the members of the present family 

 show practically no traces of the rapid and pronounced 

 changes of color described in connection with several 

 families of lizards. The scaly covering of the Lacer- 

 tidce varies greatly. The majority of the species have 

 a fine, some a granular scalation ; on the tail the scales are 

 always coarse and arranged in rings. A few have large 

 keeled scales on the back. All have large, regularly 

 arranged shields on the head. The abdomen is covered 

 with large smooth shields arranged in regular transverse 

 rows. In their distribution these lizards cover an enor- 

 mous area. They occur generally in Europe, Asia and 

 Africa, being most abundant in number of species in 

 the latter continent. None is found in Madagascar nor 

 in Australia and but a few in the East Indies. 



By far the greater number of species of the Lacer- 



