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. II 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. Ill 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 7° mm. 



greatest distal width 5° mm. 



Tibia, total length 149 mm. 



greatest proximal width 5 2 mm. 



greatest distal width 5° mm. 



Fibula diameter of shaft 9 mm. 



Astragulus, length 23 mm. 



width 24 mm. 



Calcaneum, length ° 2 mm. 



Metatarsus II, length 45 mm. 



Metatarsus III, length 4$ mm. 



Metatarsus IV, length 42 mm. 



Phalanx 1 of digit III, length 24 mm. 



Phalanx 2 of digit III, length 16 mm. 



Phalanx 3 of digit III, length 17 mm. 



