8 University of California Publications in Zoology [Vou.9 
List OF SKELETONS—(Continued) 
Museum 
Species number Locality Collector 
Anota macealli 1006 Salton Lake, Imperial  F. Stephens 
County, California 
Phrynosoma modestum Zool. Dept. Arizona G. W. Treadwell 
Sceloporus occidentalis Zool. Dept. Near San Leandro, Ala-  E. P. Rankin 
meda County, Califor- 
nia 
Dipsosaurus dorsalis 1878 Colorado River at Pilot J. Grinnell 
Knob, California 
Crotaphytus wislizeni 1467 Big Creek Ranch, Hum-  C.H. Richardson, Jr 
boldt County, Nevada 
Diagnostic Characters: Parietal and supratemporal elements 
and often the jugal possessing spines; superciliary ridges formed 
by processes from the frontal and prefrontals present; post- 
orbital spines small and short; epipterygoids short, only reaching 
to the petrosal; pterygoid teeth absent ; sternum broad with large 
fontanelle ; no abdominal ribs; chevron bones lacking symphyses ; 
postischial symphysial cartilage well developed. 
Description—Skull: The alveolar portion of the premaxillary 
is short and borders the nasal openings for a very short distance. 
The same openings are bordered laterally by processes arising at 
the middle of the maxillary elements. The nasals are distinct 
and form half or more of the arch over the nostrils. The un- 
paired frontal, narrowed anteriorly, where it articulates with the 
prefrontals, forms the superior arches over the orbital cavities. 
At the ends of the arches are small posterior, spiny processes and 
long, acute, anterior, superciliary processes extending forward 
over the orbits. The large prefontals send processes posteriorly 
over the orbits forming, with the processes from the frontal, the 
superciliary ridges. These two processes vary in length in the 
different species, almost meeting in some (Phrynosoma blainvillei 
blainviller, P. b. frontale) and widely separated in others (P. 
platyrhinos, P. modestum, P. douglassi). In P. cornutum they 
meet and partially ossify. The postfrontals are usually ossified. 
The lacrymals are small. The parietal overhangs the supra- 
occipital and supports several horns on its strong parieto- 
quadrate arch. The number of horns is usually two with a 
rudimentary third between, but in P. solare there are four well- 
