6 University of California Publications in Zoology (Vou. 9 
Genus Phrynosoma Wiegmann 
Anota, Cope (1866), p. 310. 
Tapaya Girard (1858), pp. 394-399, pl. 21, figs. 6-9. 
Batrachosoma Girard (1858), pp. 354-365, pl. 20, figs. 10-13. 
Doliosaurus Girard (1858), pp. 407-410. 
Many good descriptions of the genus Phrynosoma are to be 
found, but all except Cope’s (1898) are based solely on external 
characters. It is hoped that the addition here made of the more 
noticeable osteological characters will make the description more 
complete. 
EXTERNAL CHARACTERISTICS 
Diagnostic Characters: Head short, cordiform and elevated at 
the vertex; occipital and temporal regions bearing flattened and 
grooved spines which vary in length and number; cephalic plates 
small and polygonal; nostrils anterior or lateral; teeth small and 
bluntly eonieal; palatine teeth lacking; body short, suborbicular, 
ereatly depressed and usually fringed by one or two rows of 
spinose seales; back covered with scales which vary greatly in 
size and shape; scales of ventral surface, smooth and equal sized ; 
cular folds present; tail short, usually rounded and conical; 
limbs short, digit moderately developed; tympanum visible or 
covered more or less with scales; femoral pores present; preanal 
pores lacking; no dorsal or caudal erest (pl. 1). 
Description: The body is broad, flat and oval, usually with a 
lateral fringe (pl. 1). Dorsally it is covered with keeled scales 
which are irregular in shape and size. Ventrally the scales are 
small and regular, giving an imbricated appearance. Larger 
keeled scales cover the front of the arm and thigh. The head is 
short and somewhat triangular in shape with a sharp projecting 
margin. The projecting superciliary regions overhang a groove 
from the occiput to the snout, in which the eye is situated. Small 
subequal scales cover the top of the head and a row of bony 
spines, variable in length and number, are to be found on the 
temporal and occipital region. The projecting superciliary 
regions bear posteriorly short, sharp scales. Protected by bony 
processes and just in front of the interoccipital region, is the 
