154 REPTILES OF THE WORLD 



and cheered by the sun. Meal worms are a favorite 

 article of diet, but should be varied with soft-bodied 

 insect larva?, as the former block the intestines with an 

 accumulation of their chitinous bodies. Ants are a 

 favorite food and the black species should be selected, 

 as the reddish kinds reek with formic acid. In a tem- 

 perature below 70° Fahrenheit, horned lizards become 

 sluggish and refuse all food. 



The Family X enosauridce , made up of a single genus 

 (Xenosaurus) and one species, X. grandis (inhabiting 

 southern Mexico), seems to be a connecting link be- 

 tween the Iguanidce and a succeeding family — the An- 

 guidce. Boulenger explains: — "Its affinity to the 

 former is shown by the T-shaped clavicle, the absence 

 of symmetrical bony shields on the head and of osteo- 

 dermal plates on the body"; its affinity to the Anguidce 

 is evident by the structure of the tongue, which has a 

 flat, narrow and feebly incised anterior portion that is 

 retractile, and the structure of the teeth, as well as the 

 separated palatine bones. The single representative 

 grows to a length of about ten inches. The body is 

 depressed, with well-developed limbs and a fairly long 

 tail; it is covered with fine, irregular granules mixed 

 with conical protuberances. On each side of the body 

 is a distinct fold in the skin, strongly suggestive of the 



Anguidce. 



The Family Zonuridce: This also seems to connect 

 the Iguanidce with the An guidon. The dentition is 

 pleurodont. The four genera inhabit tropical and 

 South Africa and Madagascar. Zonurus is the largest 

 genus, with seven species. They are distinguished by 

 the large bony plates on the back and tail; on the lat- 

 ter they are pointed and bristling, looking much like 

 the structure of the Mastigures' tail, though propor- 



