148 
TERTfAliY YERTEBRATA OF THE FAYlJM. 
'I'lio sustoiitaciilar facet (sxs.) is separated from the ectal posteriorly by a deep groove 
which enlarges anteriorly into a deep fossa ; this surface is convex from before back- 
wards and anteriorly it is continued forwards and outwards as a narrow strip along the 
to]) of the anterior edge of the above-mentioned fossa, and in front of this it is continuous 
with the small surface for the navicular which meets it at about a rio-ht amrle. The 
sustentaculum, as a whole, is prominent and sharply defined. The cuboid surface (cub.) 
Text-fig. 51. 
Left calcaneum of Palceomastodon heachielli : A, from above ; B, distal end. 
cub., facet for cuboid ; ec., ectal facet ; sms., susteutacular facet ; t.c., tuber calcis. 
The libular facet lies immediately outside the ectal facet. | uat. size. 
is much like that seen in Elcjjhas, but is narrower and does not extend so far towards 
the inner side of the bone ; it is gently concave. Jleneath and to the inner side of it 
there is a roughened surface which ventrally passes into a prominent tuberosity. The 
outer face of the calcaneum is concave from above downwards, while the inner side of 
the t/fber calcis is slightly convex, the whole tuber being much more compressed 
laterally than in Elephas, though perhaps not more so than in Tetrabelodon amjustidois. 
}so astra(jalas largo enough to have belonged to P. beadnelli has been found; but a 
