94 DINOCKKATA. 



is concave in its outer luilf, juid convex in its inner linlf, while in the 

 rliiTioccros, siicii ;i section is concave at each end, and convex only near 

 the iiiciliiiii iMirlioii. 



( >u tli(^ side of the radius toward the idna, is a narrow articnlar 

 smracr Inr tii;it lione, IxM-oniiiiy broiider toward the outer end. 



Tlic sliiiri of iIk^ riidiiis is smallest at a point about one-third of the 

 wiiv from tlic proximni, toward the (list;il end. Above this jtoint, the 

 bone cxiijiiids riitiicr rii|)idly toward llic head. It is nuch roughened, 

 espcciidh on llie side toward the ulna, with which, however, it forms no 

 boii\' union; nor arc tln^ bones I'ou^liened, or j^rooved for close adaptation 

 to each otiier, as in tiie tapir and riiinoceros The bicipital tuberosity is 

 \\('ll developed, and |i!aced I'atlier low down on the side of the shaft, 

 instead of on tlie front part of it. The distal end of the shaft is large, 

 roug'h, and oblique, and presents no smooth grooves for tendons. 



The distal articular face is divided by a median ridge into two 

 sub-equal facets, for the scaphoid and lunar bones of the carpus. Tiiese 

 facets are confluent along the summit of the median ridge. That for the 

 scaphoid is semi-circular in outline, and concave in both directions, while 

 that for the bniar is foui'-sided, niucli bioader in front than behind, and 

 concave througliout. Ncuir the back part of the ulnar side of this facet, 

 the articular liu-e is continued into a, small tract on the lateral surface of 

 the radius, where it. comes in contact witli the ulna. 



The shaft of tlie radius has an interior cancellated structure, as shown 

 in the hgurcis below, but no medullary cavity 



Figure 108. — Section of nii'ms of Dinoceras mirahile, Marsh (No. I19B). 

 FlGDRE 109.— Section o( nxdinti oi JMuoctras mirahik, Marsli (No. 12:!4). 



Botli tignrus aro mio-foiirtli natural .size. 



Measurements of the radius in thre(^ iiulividuals of J>i»oceras are the 

 followiii"' : 



