24 
inward by a strong ridge which proceeds upward and slightly backward, 
from the hinder end of the jugal contact, and ends thinly above between 
the prefrontal and the nasal at a much higher level than the postero- 
external limit of the bone above. In this inner thickening is a large 
perforation which leads forward, from the concave, interorbital posterior 
face of the bone, through to the free internal surface which is vertically 
concave, the amount of concavity decreasing forward. The thin apical 
portion of the maxillary fits closely from below within the lachrymal in 
the latter’s anterior half, and continues downward the internal concavity 
of the lachrymal. In the description of the maxillary mention has already 
been made of the double foraminal opening below the internal concavity 
of its apex. This concavity passing from the lachrymal to the maxillary 
marks the course of the lachrymal canal from the large perforation in 
the lachrymal to the above-mentioned maxillary foramen which latter 
apparently connects obliquely forward and downward with the large 
external foramen in the maxillary situated in advance of the anterior 
end of the lachrymal and almost hidden by the lower border of the pre- 
maxillary limb. The internal maxillary foramen also leads backward 
and connects with an opening in the deep, vertical groove which is present 
behind the base of the apical portion of the maxillary. 
In describing the type skull of Gryposaurus^ the writer mentions the 
posterior opening of the lachrymal canal which has a position similar to 
that in the present genus. 
Measurements of Right Lachrymal of Specimen Cat. No. 2289 {disarticulated skull). 
Mm. 
Extreme external length, in a straight line 180 
Extreme external depth 80 
Posterior opening of lachrymal canal — 
Vertical diameter 40 
Tran.sverse diameter 23 
Figure 11. Right nasal of Edmontosaurus, Cat. No. 2289; internal aspect, 
obliquely from below; ^ natural size. F, frontal; L, lachrymal; mx, surface for 
maxillary; N, nasal; pmx, surface for upper limb of premaxillary; Prf, prefrontal. 
Nasal (N.). Figures 3, 4, 5, 8, 9, 10, and 11. The nasal bone is long 
and narrow and is in contact with its fellow along the longitudinal midline 
of the skull except for about one-fourth of its length in front where the two 
are separated by the upper premaxillary limbs. It is slender for the whole 
of its length except in the anterior half of its posterior half-length where 
iThe Ottawa Naturalist, vol. XXVII, 1914. 
