OSTEOLOGY OF POLYGLYPHANODON—GILMORE 241 
Dentary.—The dentary gives support to 19 teeth, and viewed from 
above, as in figure 21, it has a sinuous dental border, the anterior end 
curving inward to meet its fellow of the opposite side. On the inner 
side of the anterior end a rounded, flattened surface indicates the extent 
of their union at the symphasis (see fig. 20). The dentary-surangular 
suture lies below the anterior half of the coronoid, much as in Peléo- 
saurus. 
Angular.—The angular (an) in a lateral view is slightly visible on 
the mid lower border and again where its posterior extremity turns 
upward toward the articular. In its limited participation in the 
lateral surface of the ramus, the angular has its closest approximation 
in the Agamidae. On the inner side it probably underlies the pre- 
articular and at the forward end is in contact with the splenial and 
dentary. On the inner side near the upper anterior end the angular 
Figure 20.—Left ramus of Polyglyphanodon sternbergi Gilmore, U.S.N.M. No. 15477, type, 
internal view, natural size: an, Angular; ar, articular; c, coronoid; d, dentary; par, pre- 
articular; sa, surangular; sp, splenial. 
is perforated by a small foremen (see fig. 20). Its long tapering 
anterior extremity is intercalated between the splenial and dentary. 
Surangular.—The surangular (sa) is relatively short and deep and 
comprises practically all the area between the dentary and the articular 
cn the external side of the ramus, as clearly shown in figure 16. Near 
its posterior end a prominent sharp ridge extends from the anterior 
border of the cotylus diagonally downward and forward across the 
whole depth of the bone, much as in Cyclura. On the inner side a 
nearly vertical suture shows its union posteriorly with the articular 
(see fig. 20). Anteriorly it unites with the coronoid. Its sutural 
articulation with the prearticular is so fully coalesced that it cannot 
be traced in any of the materials now available. 
Coronoid.—The coronoid (¢) rises prominently above the general 
level of the ramus, with a decided backward bend near its upper 
extremity. On its inner side a sharp median perpend:cular ridge 
extends from almost the top to the bottom of this bone, thus giving 
it additional strength. The ventral border on the internal side prob- 
ably meets the anterior end of the prearticular, but the sutures in all 
