26 
margin of the narial opening. The outer anterior area, occupying the 
remainder of the bone’s breadth, is bounded externally by the raised 
inwardly retreating border of the expanded snout. It is not so sunken 
as the first but becomes moderately deep outwardly. It is marked off 
from the subnarial area by a sharply defined difference in the amount of 
depression in the two. The third or subnarial area is much longer than 
broad, occupies the entire breadth of the lower limb, and extends at either 
end slightly past the narial opening. Its depressed surface, which is deepest 
anteriorly, has an outline that, taken in conjunction with that of the 
opening, forms an irregular, lengthened oval. Its curved posterior demar- 
cation continues downward the marginal protrudence of the nasal already 
referred to as occurring at the posterior end of the narial opening. 
Maxillary. (Mx.). Figures 3, 4, 12, and 13. This element is slightly 
over two and a half times as long as high and in lateral aspect has roughly the 
outline of an isosceles triangle of which the base, represented by the straight 
Figure 12. Left maxillary of Edmontosaurus, Cat. No. 2289; \ natural size. A, view from 
without; B, view from within, amn, anterior maxillary notch; amp, anterior maxillary process; 
ept, surface for ectopterygoid; j, for jugal; I, for lachrymal; n, for nasal; pal, for palatine; pmn, 
posterior maxillary notch; pmp, posterior maxillary process; pmx, surface for lower limb o 
premaxillary; pt, for pterygoid. 
