4 
Through the courtesy of Dr. W. A. Parks, Director of the Royal 
Ontario Museum of Paleontology, and his staff, the writer was able to 
study the fine collections of hooded hadrosaurs in the Museum at Toronto 1 . 
Mr. Bamum Brown, of the American Museum of Natural History, New 
York, has kindly supplied measurements of the fore limbs of Corythosaurus 
casuarius . Miss Alice E. Wilson gave valuable assistance in choosing 
specific names. The drawings were made by Mr. J. S. H. Lefebvre. 
COMPARISON OF BELLY RIVER FORMS 
In comparing Corythosaurus and Lambeosaurus too much attention 
may have been paid to superficial resemblances, and perhaps it has not 
been fully realized that the premaxillsa and nasals contained ramifications 
of the narial passages and air reservoirs, which were different in the two 
genera. Parks compares the spike or process in Corythosaurus intermedins 
(14, page 9) with that of Lambeosaurus lambei, but in one case this is 
made up of nasals only and in the other of the nasals and premaxillae. The 
most noticeable differences between Lambeosaurus and Corythosaurus seem 
to be shown in the development of the premaxillae and nasals. These dif- 
ferences are linked with the development of the narial passages and no 
doubt had considerable influence on their feeding habits. A number of 
published restorations of Corythosaurus show the hood or helmet-like crest 
as a thin cockscomb rather than a fairly thick hood containing narial 
passages and subsidiary air reservoirs. The cheeks are much fuller and 
the mandible broader posteriorly than is usually shown. 
The pelvic arch is quite different in the two genera. In Lambeosaurus 
the integument was made up of small scales, not differentiated into patterns 
and without limpet-like bosses such as are seen in Corythosaurus. 
The narial passage in Tetragonosaurus seems to be similar to that of 
Corythosaurus . In Hypacrosaurus from the Edmonton formation, as will 
be described later, the narial passage follows a totally different course. No 
specimen of Parasaurolophus is available for study, so this genus is not 
considered here, but there seems to be no question that it should be placed 
with the Lambeosaurinae. 
Family, Hadrosauridae 
Subfamily, Lambeosaurinae Parks 
Genus, Corythosaurus Brown 
Corythosaurus excavatus Gilmore 
Can. Field-Nat., vol. 37, pp. 46-7, March, 1923 
Plesiotype . No. 8676, Geol. Surv., Canada, consists of nearly complete 
skull and skeleton back to sacrum (skeleton only partly prepared). Col- 
lected by the writer in 1919. 
Horizon, Pale Beds, Belly River series, Upper Cretaceous. 
Locality . About 3 miles south of the mouth of Little Sandhill creek, 225 
feet (aneroid) above the level of Red Deer river, Alberta. 
Generic Characters (emended). Hood or helmet-like crest variable; 
facial slope variable; lower limb of premaxilla extending backward and 
1 Sinee this paper was prepared Dr. Parks has described three new species of hooded 
hadrosaurs (Univ. of Toronto Studies No. 37, 1935). 
