2 
articulated, well preserved with remarkably little distortion, in a soft 
clayey sandstone easily removed and leaving the surface of the bones 
clean. This particular state of preservation provided an opportunity 
for study and description seldom accorded. A preservation of this nature 
was especially welcome in the skull as in the generality of cases the elements 
of the skull in dinosaurs are found in place and are not easily freed from 
each other. Any particular bone is largely hidden by the surrounding 
ones, and it is a matter of difficulty, often of impossibility, to remove it 
in order to see it in all its aspects. Also, when a skull is preserved with 
the elements in place any distortion that may have occurred is likely to 
affect all of the elements to a greater or less extent. In a naturally dis- 
articulated skull, distortion when present in any particular bone is confined 
to the limits of that bone. With few exceptions all the drawings repro- 
duced in this memoir in illustration of the text were made by Mr. Arthur 
Miles under the supervision of the writer. 
MATERIAL ON WHICH EDMONTOSAURUS IS BASED. 
Edmontosaurus is represented in the collections of the Geological 
Survey by remains, including the skull, of at least two individuals, as 
follows: 
Collection of 1912, Edmonton formation. Red Deer river, Alberta, 
field No. 27, Cat. No. 2288, genotype, from opposite the mouth of Three 
Hills creek, at 200 feet above the level of the river: the skull figured and 
described in this paper, with most of the vertebra} in place back to the 
sixth caudal, one hind limb lacking a few phalanges, one humerus, both 
pubic bones together, one ischium, the greater part of the right ilium, 
and some ribs. Estimated length of individual considerably over 30 feet. 
From field measurements the length of the following bones are: femur 
47 inches, humerus 27 inches, ischium 54 inches. The discovery of this 
specimen was made by L. Sternberg, assistant on the Geological Survey 
party of 1912. 
Collection of 1916, Edmonton formation. Red Deer river, field No. 6, 
Cat. No. 2289, paratype, found by G. F. Sternberg 7 miles west and north 
of Morrin, in sec. 16, tp. 31, range 21, on the west side of the river, 90 feet 
above water level: a skeleton lacking some of the bones of the feet, the 
tail vertebrae behind the fifth caudal, the premaxillaries and the predentary. 
There is a possibility of the right ilium not being present. The bones 
of this individual are splendidly preserved and lay closely scattered within 
a grey, clayey sandstone which is easily removed leaving the surfaces in 
good condition. The elements composing the top of the skull are pre- 
served together. The remaining bones of the head, including the mandi- 
bles, were found disarticulated. Femur 49 inches long, humerus 27 J 
inches, left ulna 30 inches, left radius 26 inches, largest right rib 50 inches 
along the curve, dentary 30 inches, depth of dentary in advance of base 
of coronoid process, from the lower surface to external alveolar border 
6| inches. 
Of the type skeleton the skull only (Figures 3 and 4) has as yet been 
prepared. This work was skilfully performed by L. and C. M. Sternberg. 
