23 
Figure 10. Right lachrymal of Edmontosaurus, Cat. No. 2289; i natural size. 
A, external aspect; B, internal aspect; C, posterior aspect; L, lachrymal; N , nasal; 
Prf, prefrontal; j, surface for contact with jugal; pmx, with premaxillary. 
Lachrymal (L.). Figures 3, 4, 5, 8, 9, 10, and 11. This bone is over 
twice as long as high, and somewhat wedge-shaped, being thickest behind 
and thin toward the front. It is in contact with the nasal, prefrontal, 
jugal, maxillary, and premaxillary. When in position in the skull its 
length is in the direction of that of the lower premaxillary limb. 
Viewing the lachrymal in position from without it presents a surface 
with an irregularly four-sided outline broadest behind and pointed in 
front. Supero-anteriorly it is largely hidden beneath the termination of 
the premaxillary limb. It is overlapped supero-posteriorly by the pre- 
frontal for a considerable distance. Interiorly it unites for the whole of 
its length with the jugal. The posterior border comes to a sharp edge 
which is decidedly protrudent outward in its upper part. This border is 
free and forms that portion of the orbital rim between the prefrontal and 
the jugal where it projects backward into the orbit to a considerable 
extent. The lachrymal contribution to the orbital rim is mostly below 
the midheight of the orbit. Postero-inferiorly, at the back end of the 
jugal contact, it extends a stout, pointed process downward behind the 
jugal. The external surface is somewhat convex in a direction at right 
angles to its length. 
In the disarticulated skull. Cat. No. 2289, this bone is still firmly 
attached to the nasal and prefrontal, but the jugal, maxillary, and lower 
premaxillary limb are separate from it so that its true shape and the full 
extent of the majority of its surfaces are revealed. The bone ends abruptly 
in front with little decrease in depth forward. Outwardly the surface 
covered by the premaxillary limb supero-anteriorly is large, equal in area 
to about one-half of the entire external surface. The outer overlap of the 
prefrontal above is small, as is also that of the jugal below. 
The inner surface of the lachrymal, revealed in the disarticulated 
skull, is interesting. Toward its posterior end the bone is greatly thickened 
