262 PROCEEDINGS OF THE NATIONAL MUSEUM VOL, 92 
subovate in outline and bifossate. The anterior face of this bone is 
concave with its upper and lower margins raised. The distal end 
presents a small rounded facet that looks forward and downward, and 
posterior to it a narrowed articular surface that extends upward on 
the posterior face for more than half its length. 
The calcaneum is smaller than the astragalus, with a cupped articular 
upper surface for the fibula that is oblique to the longest planes of the 
Ficure 36.—Left hind foot and part of tarsus of Polyglyphanodon sternbergi Gilmore, 
U.S.N.M. No. 15568, natura |size, restored from both hind feet [the astragalus and cal- 
caneum (reversed) from type specimen, U.S.N.M. No. 15477]: as, Astragalus; ca, cal- 
caneum; ¢, tarsalia 3 and 4; I, II, III, IV, and V, digits 1 to 5 respectively. 
coalesced bones. The inner ventral surface is recessed by an oblique 
facet that looks downward and inward; a second smaller facet is 
present on the extreme outer distal end which probably articulated 
with tarsale 5. A flattened but irregular shaped element in the 
articulated right foot at the upper end of metatarsal IV and in articu- 
Jation with metatarsal V probably represents tarsale 4. A small 
subtriangular element present in both hind feet at the end of meta- 
carpal III is regarded as tarsale 3. Its position is shown in 
figure 36. 
