MEMOIRS OF THE CARNEGIE MUSEUM. 
times small emarginations which touch corresponding surfaces on Me. II when the 
duplex is thrown back against the dorsal or radial faces of the metacarpal. This 
feature is shown in numerous specimens, in some more decidedly than in others, 
The proximal end of the duplex is expanded more on the ulnar side than on the 
radial, corresponding to the development on the ulnar angle of the distal end on 
Me. II to which reference has already been made. The posterior portion of the 
plantar face of the duplex is taken up largely by a very broad tendinal groove. 
Midway between the proximal and distal ends there is, on the plantar face, a rough 
ridge located transversely which marks the junction of the two coéssified phalanges. 
This ridge may be traced (see Fig. 91, 1, 2) around the entire bone and the dorsal 
face is seen to present a heavy elevation where the two bones are united. The 
distal trochlea is rather an imperfect pulley-shaped groove, there being a decided 
shoulder near the dorsal border of the trochlea to check the ungual phalanx when 
flexed dorsally (see Fig. 91, 2). Besides this dorsal shoulder there is usually a 
transverse ridge nearer the palmar face which interrupts the pulley-like groove 
and apparently rather forms a lock for the terminal phalanx. The terminal 
phalanx has a corresponding buttress on the proximal termination of the median 
keel and a cross-groove to correspond with the ridge on the duplex just described, 
and is thus seen to have a limited flexure. The same arrangement is found in the 
large Chalicothere from Pikermi. 
The ungual phalanx of the second digit in Moropus is very heavy and its 
surfaces are rugose, indicating that it was covered by a heavy claw-like hoof. 
Fic. 91. Fie. 92. Ungual phalanx of digit II of right manus of 
imal and median phalanges of digit IT of left M. elatus (No. 1604). X}4. 1, lateral view; 2, proximal 
manus of M. elatus (No. 1604). X43. 1, lat- view. 
eral view; 2, dorsal view. 
The bone is high, laterally compressed, not extremely long, but deeply cleft anteri- 
orly for a firmer attachment to the horny sheath. The articulation for the duplex 
bone is concave supero-inferiorly and divided by a prominent median ridge, which 
