112 



DINOCERATA. 



the other bones o-f the foot. The surface is strongly rugose, and, in this 

 view, notliing- can be seen of the articular faces. 



The lateral surface turned toward the trapezium presents an articular 

 face for luiion with that bone. An ordinary form of this face is shown 

 in figure 8, but it is of variable form and size. Sometimes it even extends 

 obliquelv across the lateral surface of the bone, and becomes more or less 

 widely confluent with the articulation for the metacarpal, along the 

 anterior pai-t of its lateral border, as in woodcut 11!) below. 



Figure 119. — LelX trapezoid of Dinoceras mirabile, Marsh (No. 12.S0); side view. 

 Figure 120. — The sairre bone ; distal end. 



mvJJ. face for second metacarpal ; s. face for scaplioiii; tm. face for trapezium. 

 Both figures are one-half natural size. 



The posterior, or palmar, aspect of the bone (figure 9) shows its 

 wedge-like form, but the articular faces visible are seen only obliqueh'. 



The side turned toward the magnum (figure 10) lias an articular 

 surface extending across the bone. Usually, this surface is near the 

 anterior part of the bone, and sometimes, as in the specimen figured, is 

 more or less interrupted at the middle by a ridge. This surface may 

 also be broadly continued to the posterior, or palmar, end of the scaphoid 

 articular face, as in number 1505. 



The upper ulnar angle of this specimen is rounded for articulation 

 with the lunar. This portion of the bone may represent the central, 

 coalesced with the trapezoid, as in the existing Dendrohijrax. 



The proximal articular face (figure 11), joining the scaphoid bone, is 

 narrowly oval in outline, broader in front than behind, and more or less 

 concave in both directions. 



The distal face is somewhat similar in shape to the proximal, but 

 sometimes shorter and broader, and is slight!}' convex in one, or both 

 directions. 



