48 THE DESEADO FORMATION OF PATAGONIA 
external margin for the vestige of Mt. V. The internal 
face carries a boss beveled above by the facet for the navic- 
ular, and below by the facet for the ectocuneiform. 
All the metatarsals are short and heavy as compared 
with those of Theosodon. Mt. Il is compressed above, 
but enlarges below into a subcylindrical bone, ending in an 
extensive articular trochlea for the phalanx, the trochlea 
carrying a carina which extends into the upper surface of 
the articular area. Proximally, it is so closely approxi- 
mated to the adjacent metatarsus that these could have 
had very little independent movement. On the upper 
internal surface, there is a roughened area, where the endo- 
cuneiform overlaps this bone. Mt. III is slightly heavier 
than the others. On the distal end, its articular trochlea 
extends well onto the dorsal surface, as does also the carina. 
Mt. IV is a trifle shorter than the others and stouter. 
Mt. V is absent but its former presence is indicated by 
the beveled facet on the cuboid, and by the small roughened 
surface on Mt. IV. 
The phalanges of the third digit are a trifle heavier than 
those of the other two digits, but of approximately the 
same lengths. The ungual phalanges were broad com- 
pressed hoofs, without traces of clefts. 
MEASUREMENTS OF THE HIND LIMB 
Femur, length from the head 177 mm. 
greatest proximal width 70 mm. 
greatest distal width 56 mm. 
Tibia, total length 149 mm. 
greatest proximal width 52 mm. 
greatest distal width 56 mm. 
Fibula diameter of shaft 9 mm. 
Astragulus, length 23 mm. 
width 24 mm. 
Calcaneum, length 62 mm. 
Metatarsus IT, length 45 mm. 
Metatarsus III, length 48 mm. 
Metatarsus IV, length 42 mm. 
Phalanx 1 of digit ITI, length 24 mm. 
Phalanx 2 of digit ITI, length 16 mm. 
Phalanx 3 of digit III, length 17 mm. 
