16 
detailed statement of the actual and missing parts of this skeleton it 
will be seen that it is a most important specimen. The mounted skeleton 
has a greatest length from the front of the beak to the tip of the tail of 
32 feet 8 inches, of which the restored tail constitutes 14 feet 9 inches. 
OSTEOLOGY OF THE SKULL AND LOWER JAWS 
The skull of Thespesius edmontoni closely resembles T. annectens in 
all particulars so far as they can be compared, but is slightly smaller. It 
is long and narrow, with the facial portion elongated, and with a moderately 
expanded beak. This muzzle appears to have been rugose, and in life, 
with the predentary of the lower jaw, was probably covered by a horny 
integument or sheath, as in birds and turtles. 
The orbit is large, subtriangular in outline. It is bounded above by 
the prefrontal, frontal, and postorbital bones; posteriorly by the postor- 
bital bar formed by the slender processes of the postorbital and jugal; 
below by the jugal; and anteriorly by the jugal, lachrymal, and prefrontal. 
The infratemporal fossa is also large, but relatively narrow fore and aft. 
It is bounded above by the postorbital and squamosal, below by the jugal, 
and posteriorly by the jugal, quadrate, and squamosal. 
The narial orifice, as Marsh has pointed out 1 , in T. annectens “is an 
enormous lateral cavity which includes the narial orifice, but was evidently 
occupied in life mainly by a nasal gland, somewhat like that in the existing 
monitor and seen also in some birds”. The outlines of this cavity in the 
present skull are even more strongly marked out than in the specimens 
studied by Marsh, and the posterior bony septum separating the two 
orifices extends somewhat farther forward than in the Lance skulls. This 
orifice lies largely within the premaxillaries, though bounded posteriorly 
and above also by the nasals. The bar above the orifice appears to be 
relatively heavier than in T. annectens. 
The jugal, quadratojugal, quadrate, postorbital, and squamosal, are 
as in T. annectens, except that the descending branch of the postorbital has 
a decidedly cupped depression at midlength on its lateral surface. This, 
however, may be a malformation from an injury received in life. 
The quadrate has a length in relation to the total length of the skull 
of 1 to 2*75, whereas in the Lance skulls this proportion is 1 to 2*90. In 
the large Edmontosaurus from this same formation it is 1 to 2*50. This 
would not appear to bear out Lambe’s 2 contention “that as time pro- 
gressed the skull in the Hadrosaurinse, as a general rule, became lower”, 
for T. edmontoni from the generally regarded earlier formation is certainly 
very closely allied to T. annectens from the Lance. 
The parietal bones viewed from above are very much reduced, appear- 
ing on the superior surface as a very narrow ridge separating the supra- 
temporal fossae, and terminating behind in a point and separating the 
squamosals on the median line. 
The frontals are relatively short and wide and contribute to the form- 
ation of the median upper border of the orbit. The frontal region is deeply 
concave in transverse section, but this feature may have been exaggerated 
by the pressure to which this skull was subjected. 
1 U.S. Geol. Surv., 16th Ann. Rept., pt. I, 1896, p. 219. 
2 Geol. Surv., Can., Mem. 120, 1920, p. 76. 
