AliSiNOlTllElUUM. 
55 
lire the ectal (ec.), 'whicli is the smaller and is convex from before backwards, 
and the snstentacnlar (sus,), which is much larger, Hat anteriorly and concave behind. 
Left calcaneum and astragalus of Arsmoitherium zitteli : 1 a, calcaneum from above ; 1 b, distal surface of 
calcaneum ; 2 a, tibial surface of astragalus; 2 b, anterior view of astragalus; 2 c, distal surface 
of astragalus. 
cub., facet for cuboid ; ec., ectal facet ; Jib., fibular facet ; n., notch in liinder border of tibial surface ; 
nav., navicular facet ; sus., sustentacular facet ; ? t., facet for tibiale ; t.c., tuber calcis ; tib., surface for 
tibia. 2 nat. size. 
