1911] Bryant: Horned Lizards of California and Nevada 7 
median pineal eye. The lower jaw is bordered by large project- 
ing spinous plates. The neck is short, causing transverse gular 
folds which often cover the auditory aperture. The pentadactyl 
limbs are short and about equal in length, and the digits are 
moderately developed, the fourth being longest. The tail is 
short, conical, and covered dorsally with the same sort of scales 
as the back. Posteriorly the ventral scales are keeled. The 
tympanum may be naked or covered with scales. This character 
varies within species, however, and is not a good basis for divid- 
ing the genus as Cope (1898) has suggested. The nostrils are 
conspicuous and may be either on the lne joiming the super- 
ciliary region with the end of the snout or above this lne (pl. 2). 
A row of femoral pores varying in number in the different 
species from seven to twenty, are found in both sexes on either 
thigh. Those in the male are the most highly developed. The 
presence of enlarged postanal scales in the male is a dependable 
character for determining sex. Anal pores are absent. Juveniles 
may be distinguished by their small size and poorly developed 
horns. 
OSTEOLOGY 
The following description of the osteolozy was made after a 
study of complete skeletons as enumerated below. The generic 
osteology given here is largely an amplification of Cope’s (1898) 
work. 
List oF SKELETONS 
Museum 
Species number Locality Collector 
Phrynosoma douglassi Zool. Dept. Prescott, Arizona G. W. Treadwell 
douglassi 
Phrynosoma blainvillei 272 Schain’s Ranch, San Jae- Charles Camp 
blainvillei 
Phrynosoma blainvillei 
frontale 
Zool. Dept. 
into Mountains, Cali- 
fornia 
Kern County, California 
Phrynosoma platyrhinos 1300 Big Creek Ranch, Hum-  W. P. Taylor 
boldt County, Nevada 
Phrynosoma platyrhinos 1301 Pine Forest Mountains, Taylor and Richardson 
Humboldt County, Ne- 
vada 
Phrynosoma cornutum 4579 
