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 Crotapbytus. 



THE DESERT IGUANA; KEEL-BACKED LIZARD 



Dipsosaums 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 1 1 inches. 



Length of Jail 7^ 



Greatest Diameter if 



Width of Head* f 



Length of Head ear to snout 



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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