OSTEOLOGY OF POLYGLYPHANODON—GILMORE 2a 
SKULL 
The description of the skull is based primarily on the almost com- 
plete articulated cranium and lower jaws of the type specimen, U. S. 
N. M. No. 15477. It is supplemented by skull portions of three other 
specimens: U.S.N.M. No. 15816, the paratype; No. 15568, the greater 
portion of a disarticulated skull; and No. 15559, consisting of the 
articulated parietal and frontal and a left maxiliary. The type has 
suffered some deformation through crushing, which has obscured 
structural details of the supratemporal and postorbital arches. Except 
for this, the right side of the skull is in good preservation, though 
the left side is slightly less well preserved. 
Viewed laterally, the skull of Polyglyphanodon is subtriangular in 
outline, with heavy arches and a deep maxillary region. Except for 
the dentition the skull is normal lacertilian in all respects. The prin- 
cipal structural features of the skull are clearly illustrated in figures 
16-19, drawn from the type, with some details added from the evidence 
furnished by other specimens. 
Parietal—tThe parietal (p) is relatively short, with flattened dorsal 
surface, and is transversely constricted posteriorly to its midlength. 
On each posterior external angle long, slender, divergent processes 
form much of the inner and posterior boundaries of the supratemporal 
fossae. Between these processes the posterior border is broadly hol- 
lowed out. Both of the posterior processes are missing in the type, 
but the right is preserved in its entirety in specimen U.S.N.M. No. 
15568, and both are present in U.S.N.M. No. 15816. Anteriorly this 
bone joins the frontals by a straight, transverse digitating suture. 
This border at the center is deeply notched by the pineal foramen. 
Camp ° observes: “The foramen is usually pierced between the parie- 
tals but, in the Iguania and Rhiptoglossa, where these bones are con- 
stricted posteriorly it sometimes migrates forward to lie in the fronto- 
parietal suture.” 
The plane of the parietal is at a distinct angle to that of the frontal 
region, being depressed posteriorly. This angulation begins at the 
frontoparietal suture. On the anteroexternal angle the parietal artic- 
ulates with the postfrontal, which sends a thin, widened process back- 
ward along the side of the parietal, as shown in figure 16. Along the 
anterior end the dorsal surface is roughened by a few ridges and 
grooves that extend slightly diagonal to the median axis. At the 
center the parietal of the type specimen measures 12 mm. in length, 
with a least transverse diameter of 9.4 mm. 
Camp, C. L., Classification of the lizards. Bull. Amer. Mus. Nat. Hist., vol. 48, p. 
394, 1923. 
