30 University of California Publications in Zoology (Vou. 9 
below the rictus a large broad infrarictal spine followed by a 
smaller conical one; enlarged gular scales, in three or more double 
rows; peripheral spines in two widely separated rows, the upper 
being the largest ; back and tail covered with large scattered scales 
which are strongly keeled and tubercular, set among smaller 
seales and granules; ventral scales smooth; tail conical and 
fringed by a row of widely separated trihedral spines ; tympanum 
not covered by scales; femoral pores in long series (12-18). 
Description: The two occipital horns are strongly developed, 
flattened and grooved (pl. 4, fig. 9). A small (1-2 mm.) inter- 
occipital spine is present. The horns of the occipital region are 
raised above those of the temporal region. The nostrils are on 
the lines joming the supereciliary ridge with the end of the snout 
which is not separated from the frontal region by a prominent 
angle. There are two widely separated rows of peripheral spines, 
the upper being the largest. Three or more longitudinal rows of 
pointed gular scales, the inner rows being the smallest, are to be 
found on each side of the gular region. These rows form an 
apex at the front of the jaw and continue posteriorly onto the 
gular folds (pl. 4, fig. 10). The head shields are convex and 
almost smooth, some of the centrally situated ones being the 
largest. Four or more bony tuberosities are to be found on the 
parietal region in front of the occipital spines. The temporal 
horns are four to six in number on each side. The posterior one 
is much the largest. The postorbital spine is well developed. 
The temporal scales are ridged in the general direction of the 
temporal horns. <A series of five or six large sublabial spines 
is continued posteriorly by several smaller scales. At the 
corner of the mouth is a large, flattened seale below which is a 
large and very broad infrarictal spine followed by a smaller 
conical one. 
The back is covered with large, scattered scales which are 
somewhat elevated, keeled and tubercular and set among smaller 
seales and granules (pl. 4, fig. 9). The ventral seales are smooth 
and of equal size. Dorsally the tail is covered with the same 
sort of scales as those found on the back; ventrally the small 
equal-sized scales become keeled on the terminal portion. <A 
