5 
not separating upper limb and nasal; nasals strongly developed, forming 
much of superior, and all of posterior, portion of hood and separating 
upper and lower limbs of premaxilla posteriorly; narial passage running 
from lower to upper limb of premaxilla through S-like passage and sur- 
rounded posteriorly by subsidiary air chamber; cranium narrow; prefrontal 
well developed; maxilla slender anterior to jugal overlap; teeth more 
numerous in maxilla than in dentary; humerus much shorter than radius, 
radial crest strongly developed; ilium decurved anteriorly; pubis with 
anterior blade short and broadly expanded; ischium long, with foot-like 
terminal expansion; skin-impression with raised limpet-like bosses. 
Specific Characters. Facial slope uniformly steep; nasals short and 
high, excavated behind; narial passage open superiorly back to division of 
premaxilla; lower limb of premaxillag not reaching nasal postero-superiorly ; 
upper limb of premaxilla extending to superior tip of crest; diagonal groove 
across lower limb of premaxilla strongly developed and running into air 
chamber; 39 rows of teeth in maxilla; 36 rows in dentary; dental magazine 
shallow; edentulous portion of dentary short; predentary and homy beak 
broad in front; scapula slender, rounded posteriorly; radius 25 per cent 
longer than humerus, radial crest strongly developed; metatarsals large. 
The shorter nasal, open narial passage, slight contact between the 
nasal and lower limb of premaxilla, and fewer teeth might be regarded as 
uvenile characters were it not for the fact that these characters seem to go 
together in both large and small skulls; several specimens that are 
smaller than the type C. excavatus show the typical C. casuarius develop- 
ment. Among the skulls being studied is one considerably smaller than 
Gilmore’s type or than the types of C. intermedins Parks (14), but it shows 
the typical C. intermedins development. It would, therefore, seem that 
the above-mentioned characters are real specific differences. It is recog- 
nized, however, that there is considerable variation within the species, 
in the development of the hood and the closing of certain openings. It is 
quite to be expected that the hood would not be so well developed in 
younger animals or primitive species. 
SKULL 
When viewed from the side the facial slope is uniformly steep and the 
hood is moderately high and short. 
Premaxilla , Nasal and Narial Passage. In this species, as well as in 
other members of the Lambeosaurinae, the premaxilla was much folded and 
extended posteriorly and served the important function of enclosing the 
greater part of the narial passage. 
The premaxilla is somewhat pointed in front, but the homy sheath 
must have been broad to conform to the squarish lower beak. It divides 
into upper and lower limbs above the middle of the maxilla and just behind 
a well-defined groove that runs diagonally upward and backward and 
enters the hood under the anterior edge of the lower limb. The function of 
this groove is not known, but it may have carried some special blood 
supply. The lower end of this groove is almost directly above the large 
nfraorbital foramen. In its anterior portion the thin lower edge of the 
premaxilla is developed upward and inward to cover the narial passage. 
