28 o 
PATAGONIAN EXPEDITIONS : PALAEONTOLOGY. 
over upon it, as is the case in the Santa Cruz Toxodonta. The susten- 
taculum is prominent and bears a slightly concave facet for the astragalus ; 
it has a distinctly more distal position than in Nesodon , is much thicker 
in the dorso-plantar dimension and its articular surface is continuous 
with the facet for the navicular on the inner side of the distal end of the 
Fig. 44. 
Homalodontotherium segovice. Left pes, dorsum, X After Ameghino, except the calcaneum f 
astragalus and cuboid. 
calcaneum, while in the latter genus the two are separated. In corre- 
spondence with the longer neck of the astragalus, the portion of the cal- 
caneum distal to the fibular facet is longer than in Nesodon. The cuboid 
