The Iguanas 



to the large, arboreal iguanas of Mexico and Central America. 

 The general aspect and size appeal somewhat to the lizards of 

 a succeeding genus Crotaphytus. 



THE DESERT IGUANA; KEEL-BACKED LIZARD 



Dipsosaurus dorsalis, (Baird & Girard) 



The body is stout and rounded, with very long, gradually 

 tapering tail. In proportion to the size of the body the head 

 is very small; it is thick-set and rounded. 



On the centre of the back, from immediately behind the 

 head and extending down the greater length of the tail, is a single 

 row of enlarged scales; these are distinctly keeled. This char- 

 acteristic scalation shows a close relationship to the typical 

 iguanas. The general scalation of the body is fine and granular; 

 the scales on the tail are larger than on the body, are keeled 

 and arranged in ring-like series. 



Colouration. Pale brown above, with wavy, parallel dark 

 brown or black lines running lengthwise; these lines tend to 

 form a net-work or reticulate pattern, enclosing yellowish spots. 

 The tail is generally yellowish, with dark, ring-like markings 

 above. Pale and immaculate beneath. 



Dimensions. An adult specimen from southern Arizona, 

 was measured as follows: 



Total Length \\% inches. 



Length of Tail y 



Greatest Diameter i f 



Width of Head* 



Length of Head ear to snout f 



Length of Hind Limb 2 



Length of Front Limb if 



Distribution. Desert regions of the southwestern United 

 States and northern Mexico. The species occurs in Lower Cali- 

 fornia, the desert regions of southern California and in the Colo- 

 rado and Mojave Deserts of Arizona; it is also found in the 

 Amargosa Desert, Nevada. 



Habits. Like the other thick-bodied desert lizards, this 

 species is largely herbivorous. It feeds upon buds, small flowers 

 and tender leaves. Captive specimens will greedily eat the 



* Note the proportionately small head. 



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