332 3. IGUANIDM 



lines along the edges of the plates. Two narrow, dark 

 lines often may be seen running from the eye and the lip 

 to the upper and lower edges of the ear-opening. In highly 

 colored males the throat has a central patch of bright blue 

 which gradually fades out anteriorly and changes to black 

 posteriorly. Often many of the blue gular scales are 

 narrowly edged with very dark indigo or black. The belly 

 may have lateral patches of deep blue more or less replaced 

 by, or bordered internally with, black, or may be entirely 

 washed with blue and black. Often there is little or no cen- 

 tral streak of yellowish white, but a central stripe, as well as 

 the chest and the lower surfaces of the limbs and tail may 

 be yellowish white or more or less suffused with blue, brown, 

 or gray. Females and young are less brightly colored. 

 They are more distinctly blotched, above and laterally, 

 with brown, and the lower surfaces are yellowish white 

 often more or less clouded with blue or gray. The brown 

 blotches in females may form distinct dorsal and lateral 

 series or may be united to form cross-bars. 



Ruthven describes the coloration of specimens from Tuc- 

 son, as follows: "The color is variable, and the pattern not 

 well defined. The head above is usually mottled with dark 

 brown and yellow or light brown. A narrow brown line 

 extends along the infraorbital scutes from the canthus ros- 

 tralis, and is continued on the neck to the shoulder. A 

 similar line parallel to this one extends from the supralabi- 

 als also to the shoulder. On the nape there are usually indi- 

 cations of narrow V-shaped bands. These are rarely dis- 

 tinct with the exception of the posterior one, which forms a 

 narrow black collar that usually terminates on the side of the 

 neck. 



"On either side of the back, about five rows of scales 

 apart and two rows wide, are two longitudinal light bands 

 that are usually some shade of yellow, and may be either 



