In the Ecaudata the radius and ulna coalesce into one bone.
Radius and ulna typically avine, 2.1 in.
In the fore-limb the upper and lower series of carpal bones scarcely alternate, but in the hindfootthe astragalus overlaps the cuboid, while the fibula, which is quite distinct from the tibia(as is the radius from the ulna in the fore-limb), articulates with both astragalus and calcaneum.
The distal end of the humerus ends in a trochlea, with a larger knob for the ulna and a smaller oval knob for the radius.
The ulna is curved and rather stout; it articulates with both carpal bones; the cubital quills often cause rugosities on its dorsal surface.