34 THE DESEADO FORMATION OF PATAGONIA 
The radius and ulna were from another specimen which, 
however, was associated with a typical astragulus. The 
two bones are long, slender, strongly curved, and in con- 
tact with each other throughout their entire length, so 
that there could have been no rotary movement of the fore- 
arm. The radius is a slender bone with the proximal 
articular facet relatively small, the facet being slightly 
coneave, of ovoid outline and with the transverse diameter 
the greater. There is but a tiny band-like facet for the 
ulna situated on the posterior side near the inner margin. 
Distally, the radius widens into a heavy end with a rugose 
area on the outer side for contact with the ulna, and with 
two distal facets, a larger for the scaphoid, and a smaller 
for the lunar, the two being separated by a low ridge. 
The ulna is heavier above, with a strong backwardly 
directed olecranon process. The sigmoid notch makes 
almost a semicircle, the articular surface being broad and 
extending well onto either side of the bone. The facets 
for the radius are tiny. The distal end of this bone is 
wanting. 
MEASUREMENTS, SPECIMEN NO. 3275 
Radius, length 251 mm. 
greatest width at proximal end 28 mm. 
greatest width at distal end 36 mm. 
least diameter of shaft 16 mm. 
The femur belongs to the type specimen which is about 
5% larger than the other specimens. This bone is long 
and rather slender, with the greater trochanter rising well 
above the head, which is rounded, on a short neck, and 
has the ligamentary pit on the posterior margin. The 
thick, rugose, greater trochanter bends in over the head 
at its upper end. The lesser trochanter is relatively small, 
and prolonged into a ridge. Unfortunately the third tro- 
chanter is broken off in my specimen. The digital fossa 
is extremely large and deep. Proximally the shaft is 
flattened, but becomes rounded distally. Just above the 
