62 
of the distal end of 250 mm. Planes projected from these diameters would 
intersect one another at nearly right angles. The fibula shows no distinct- 
ive features. 
Of the tarsal bones, the calcaneum and astragulus are present and 
articulated with the tibia and fibula. In the distal row the tarsale articula- 
ting with mt. IV is present and securely attached to its cupped proximal 
surface. It is a flattened, subovate bone that measures 60 mm. antero- 
posteriorly and 40 mm. in transverse diameter. 
The metatarsals, although smaller than in the paratype of H. altis- 
pinus, bear the same relative length to the tibia as in that species. Their 
articulated proximal ends have a combined width of 230 mm. The articu- 
lated digit III measured along the curve on the front face has a greatest 
length of 617 mm. It appears that Brown was probably correct in regard 
to the metatarsals being “greatly lengthened,” in the foot of Hypacro- 
saurus, but this applies more especially in comparison with feet of the 
Lance Hadrosaurs than it does to Saurolophus or other Belly River genera. 
In any event the difference is so slight that at present it is not of much aid 
in identification. 
The phalangial formula is the same as in other hadrosaurs, and appar- 
ently the digits are of about equal length, with the possible exception of 
Saurolophus osborni. 
Comparative Measurements 
Fore Limb 
Humerus, greatest length 
Ulna, greatest length 
Radius, greatest length 
Pelvic Girdle , Hind Limb 
Ischium, extreme length 
“ length of foot 
** across iliac and pubic heads.. 
Greatest length of femur 
“ “ tibia 
“ “ tibia with astragulus 
Pubis, narrowest width of blade 
Greatest length of fibula 
“ “ metatarsal II 
“ “ “ III 
u ti it jy 
Vertebrae 
Length of first caudal centrum . . . 
Width of first caudal centrum 
Length of second caudal centrum 
Width of second caudal centrum. 
Hypacrosaurus 
altispinus. 
No. 8501, 
Geol. 
Surv., 
Can. 
Hypacrosaurus 
altispinus 
Brown, 
type. 
No. 5204, 
A.M.N.IL 
Hypacrosaurus 
altispinus, 
paratype. 
No. 5272, 
A.M.N.II. 
Hypacrosaurus 
altispinus 
Brown, 
No. 7948, 
U.S.N.M. 
510i 
665 
620 
1,000 
302 
360 
1,074 
950 
995 
115 
929 
290 
384 
333 
69 
140 
1,140 
300 
340 
120 
90 
180 
580 
750 
700 
1,060 
1,080 
1,000 
350 
430 
340 
670 
1,035 
1,000 
100 
935 
400 
60 
120 
Estimated. 
