63 
Measurements of Right Thoracic Rib {? fourth or fifth) of Paratype of Edmontosaurus. 
Mm. 
Length along antero-internal curve from the head to the lower end (about 53 1 
inches) 1 , 360 
Distance from upper end of tubercular facet to top of head 180 
Depth from top of tubercle to inner curve 140 
Depth of neck at about its midlength 75 
Thickness near lower border of same 17 
Height of capitular facet 74 
Breadth of same 35 
Height of tubercular facet 45 
Breadth of same 28 
Greater diameter of lower extremity 41 
Lesser diameter of same 24 
Greater diameter of rib at midlength 42 
Lesser diameter at midlength 21 
The ribs attached to the large posterior dorsal vertebra (Figure 32) 
are very short with a length of only about 85 mm. They decrease in 
diameter rapidly for one-third of their length outward from the transverse 
process and then retain much the same size for the remainder of their 
length. They are vertically compressed with the greater diameter equal 
to about twice the lesser one. They incline a little forward and have the 
upper surface directed slightly to the front. 
Fore Limb. 
Humerus. The humerus of Edmontosaurus is a robust bone slightly 
over four times as long as its upper transverse breadth. The radial 
crest is very strongly developed and is the most conspicuous feature 
of the bone giving to it in its upper half the great breadth common to the 
humeri of the Hadrosauridae. 
In the right humerus, Figure 34, of the paratype of Edmontosaurus ^ 
the shaft is somewhat sigmoid in its length bending backward in its upper 
half and to about the same extent forward below. The head is rather 
small and occupies a central posterior position superiorly overhanging 
the shaft. It is supported beneath by a strong buttress, with a rounded 
border, passing below into the posterior face of the shaft. It is roughened 
on the upper and hinder portions of its convexity, is deeper than broad, 
and forms the highest part of the upper surface of the bone. The inner 
and outer tuberosities extend outward on either side of, and at a lower 
level than, the head with a forward curvature which renders the anterior 
face of the bone above concave. Of the two tuberosities the internal one 
is the stouter. The radial crest extends downward on the shaft from the 
outer tuberosity as a comparatively thin flange to below the midheight 
of the bone. It keeps about the same breadth downward before it suddenly 
narrows and becoming increasingly thicker merges into the shaft. From 
the inner tuberosity an obtusely angulated ridge extends down the shaft 
with decreasing prominence to below the level of the radial crest. The 
shaft below the radial crest is thick and strong with a somewhat ovate 
outline in cross-section, the greatest thickness being anterior and slightly 
external. The lower extremity narrows slightly backward and is flattened 
on the sides. The condyles are well rounded below, narrow transversely, 
8329 — 5 § 
