32 University of California Publications in Zoology |Vou.9 
do not meet the latter. The two occipital horns (occ. h.) are 
large, flattened and grooved. The interoccipital horn (interocc. 
h.) is small and sharp. Four bony tuberosities are found on 
the parietal region (par.) just in front of the occipital horns. 
The pineal foramen (pin. for.) pierces the parietal only, in the 
specimen examined. Usually but two horns are developed on 
each of the supratemporal elements (supratemp. h.), but there 
may be a smaller third one. The posterior ones on each side are 
always the largest. Each jugal (jug.) presents three or four 
tuberosities. The postorbital (postorb.) ridges of the frontal 
possess small tuberosities directly back of the orbit. The quad- 
rates are long (5-7 mm.). The epipterygoids just reach the 
petrosal. 
The Meckelian groove is open posteriorly. The coronoids are 
heavy. The surangular is not completely ossified to the articular. 
There are no bony tuberosities on the lower mandible (pl. 2, 
fir. 4). 
Six or seven enlarged neural spines show evidence of a rudi- 
mentary dorsal crest. The transverse processes of the sacral 
vertebrae are heavy and strong, those of the first caudal vertebrae 
about as long as those of the second and third. The chevron 
bones are well developed. The xiphoid rods are widely separated 
from the three sternal ribs (pl. 8, fig. 18). The ossified post- 
ischial symphysial cartilage is four to five millimeters long and 
is not bifid (fig. A). 
The name P. coronatwm has sometimes been used to include 
two species (Boulenger, 1885; Gentry, 1885; Ditmars, 1907), one 
of which presents at least two distinet subspecies. Although in 
general outward appearance P. blainvillei and P. coronatum are 
much alike, yet the latter is easily distinguished by its long, 
sharp, occipital horns, its well-developed interoceipital, its four 
well-developed supratemporal horns and by the lack of a conical 
spine behind the infrarictal, the presence of two rows of peri- 
pheral spines on the tail, and the dark-colored, equal-sized head 
plates which are outlined with light-colored lines at the sutures. 
P. coronatum is distinctly a Lower California species, yet it 
ranges far north of its type locality, Cape St. Lucas, Lower 
California, and has even been reported from San Diego (Cope, 
