PROTHEOSODON CONIFERUS 47 
from the ectal. On the external side the astragulus carries 
an expanded articular facet for the inner side of the fibula, 
which, instead of being vertical, is expanded below, mak- 
ing an oblique face which is continuous with the fibular 
facet on the caleaneum. In this feature Protheosodon is, 
as far as the feet are known, unique. 
The caleaneum is a long bone with a club-shaped expan- 
sion of the upper end. The fibular facet is small, being 
continuous, as above described, with that on the outer 
side of the astragulus. On the face toward the astragulus, 
the ectal facet is broadly convex (not divided as in Theo- 
sodon), while the sustentacular facet is slightly concave. 
The distal end is occupied by the large concave facet for 
the cuboid. 
The navicular is of moderate height, with a prominent 
hook behind. On the upper surface is only the broad, 
deep facet for the astragulus; while the lower surface is 
divided into facets for the three cuneiforms, and the ex- 
ternal distal margin is beveled to make a narrow facet for 
the cuboid. This navicular differs from that of Theosodon 
in that the facet for the ectocuneiform is not cut step-like 
into its external face. 
The endocuneiform is a small scale-like bone with a 
narrow facet on the navicular, and overlapping the inner 
side of Mt. II. The mesocuneiform is small, with a flat 
facet above for the navicular, and a convex one below for 
Mt. II, which is carried wholly on this bone. The ecto- 
cuneiform is far the largest of these three bones, and car- 
ries a broad facet above for the navicular, a similar one 
below for Mt. III, a small facet on the internal side for the 
mesocuneiform and a second one below that for the side 
of Mt. II, while externally there are facets for the cuboid 
and for the side of Mt. IV. 
The cuboid is large, the external side being longer than 
the internal. The upper surface is entirely occupied by 
~~the facet for the calcaneum, while the lower face is mostly 
devoted to the facet for Mt. IV, with a narrow streak on the 
