56 
In the maxillary magazine there are from fifty-one to fifty-three 
vertical rows of teeth. The enamelled face of these teeth is narrower 
than that of the dentary, the median keel is higher in the upper or basal 
portion of the tooth, the margins toward the apex are more elevated, 
and, in the smaller teeth at either end, are crossed in an oblique direction 
by numerous papillose ridges. The outer enamelled faces of the teeth 
do not combine as on the inner side of the dentary magazine to form a 
continuous fluted surface but present a rather irregular, longitudinal 
row of crowns in which the less protrudent or non-functioning teeth are 
seen, where the roots of the used up teeth have dropped out, deep-set 
between the functioning ones. The maxillary teeth seem to have been, 
in the cutting surface, in a single, longitudinal row in successive sequences 
of three showing a progressive amount of wear. It is possible, however, 
that in individuals of this genus, two maxillary teeth of the same vertical 
series may have been in the cutting surface near the mid-length of the 
magazine at the same time. 
The cutting surface of the dentary magazine of teeth met that of the 
maxillary magazine in a shearing action after the manner of the blades 
of scissors. In many jaws of hadrosaurs these cutting tooth surfaces 
are not in an even plane longitudinally but are more or less undulatory 
as the result of unequal wear of individual teeth. For the same reason 
an unevenness of the surface in a transverse direction was frequent. The 
effectiveness of the jaws as shears was dependent on the evenness of the 
cutting surface of the dental magazines and the frequent occurrence 
of irregular curvature in these composite dental surfaces can be taken 
only as evidence of the inefficiency of this particular kind of dentition 
except for cutting and chopping the softest and most succulent of plants. 
Measurements of Teeth of Edmontosaurus, Cat. No. 2289. 
Teeth of right dentary: 
Non-functioning tooth of average size of those near the midlength of the 
magazine — 
Height of inner enamelled surface 
Maximum breadth of same at midlength 
Breadth at lower end of same 
Non-functioning tooth from seventh vertical row from the front — 
Height of enamelled surface 
Breadth of same at midheight 
Breadth of same at lower end 
Non-functioning tooth from seventh vertical row from the back — 
Height of enamelled surface 
Breadth of same at midheight 
Breadth of same at lower end 
Mm. 
34 
11-5 
6 
26 
10 
5 
19 
9 
4 
Teeth of left maxillary: 
Functioning tooth in twenty-fourth vertical row from the front — 
Height of outer enamelled surface 27 
Breadth of same at midheight 8*5 
Breadth of same at upper (basal) end 7 
Functioning tooth in fifth vertical row from the front — 
Height of enamelled surface, about 17 
Breadth of same at midheight 7 
Functioning tooth in ninth vertical row from the back— - 
Height of enamelled surface, about 17 
Breadth of same at midheight 7 
