1911] Bryant: Horned Lizards of California and Nevada 47 
articulate for nearly their whole length, leaving the hiatus to 
run between them for a proportionally short distance. The 
basipterygoid processes are long (3-4 mm.). The slender epip- 
terygoids reach the sharp anterior edge of the petrosal. The 
quadrates are short (4 by 2 mm.). 
The lower mandible presents several spinose tuberosities on 
each side (pl. 2, fig. 5). The coronoids are small and thin. The 
Meckelian groove is nearly closed with cartilage. The articulars 
are partly fused to the surangulars, leaving but a faint suture. 
A few enlarged neural spines just back of the pectoral girdle 
show the rudiments of a dorsal crest. The second pair of trans- 
verse processes from the sacral vertebrae are small and slender. 
The well ossified postischial symphysial cartilage is six milli- 
meters in length and is bifid at its tip. The slender transverse 
processes of the caudal vertebrae are present to near the end of 
the tail. The transverse processes of the first caudal vertebri 
are nearly as long as those of the second or third and curve 
posteriorly, so that their tips almost touch the second pair of 
processes. 
In the skeleton of this species one peculiarity, that of the 
joining of the third pair of sternal ribs to the xiphoid rods, 1s 
interesting (pl. 8, fig. 19). Every other species studied showed 
the xiphoid rods widely separated from the third pair of sternal 
ribs. If there were a marked lengthening of the body so that 
a strengthening of the floating ribs would be of value, this 
migration of the third pair of ribs could well be understood. 
The ratio of length to width in Phrynosoma platyrhinos is very 
nearly the same as in the other species, so that this explanation 
hardly seems sufficient. This character being unique, at least 
among the five species and subspecies studied, it can well be used 
as diagnostic of this form. This species and A. maccalli alone 
among the species examined showed a postischial symphysial 
cartilage with a bifid tip. 
HAasits 
Phrynosoma platyrhinos is truly a desert species and is found 
in the most arid and barren places. During the heat of the day 
it usually keeps in the shade or buries itself beneath the sand, 
