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University of California Publications in Geology [Vol. 13 



respect from that of Eumetopias, but the articulation cavity for the 

 scaphoid, lunar, and centrale is much shallower. The articulation 

 tuberosity for the ulna is more or less flattened and not so distinct 

 as in Eumetopms. 



Only the distal portion of the ulna (fig. 10) was found. It resem- 

 bles in some respects that of Eumetopias. The head of the ulna is 

 flattened while the cylindrical styloid process projects distally. The 

 articulation surfaces of both the styloid process and the head lie in 

 the same plane. In Eumetopias the head of the styloid process is 

 rounded, but in this specimen it is flattened. 



An interesting feature of the trapezium (figs. 11a, 11&) is the 

 presence of a large proximal tuberosity on the radial face. The ulnar 

 face of this bone is somewhat different from that exhibited by the 

 modern Eumetopias. The facet for the trapezoid is roughly triangular 

 and occupies about one half of the ulnar face. There is also a more 

 extensive area, considerably roughened, for the attachment of muscles 

 and ligaments on this ulnar face, while in Eumetopias the same area 

 is confined to a small, but somewhat deepened subquadrangular area 

 near the distal margin, and central in position. 



On the proximal surface of the trapezium is an articular facet for 

 the scaphoid or possibly for a consolidated scapho-lunar-centrale. The 

 dorsal margin of this facet is considerably higher than the plantar 

 border; then, too, the plantar border is conspicuously rounded over 

 onto the plantar face. In Eumetopias the two margins, dorsal and 

 plantar, are more nearly equal in height. The scaphoid in our form 

 did not glide over the inner face for some distance as it does in 

 the latter. This facet traverses the proximal face in such a way as 

 to avoid completely the proximal tuberosity. A modified condition 

 is present in Eumetopias, for this same facet runs transversely from 

 the radial to the ulnar face, being reduced to a mere vestige or con- 

 siderably worn down, and as a result it extends down for some distance 

 on the radial face. 



A very different plantar face is exhibited by these two forms. 

 Eumetopias presents a relatively smooth, slightly depressed face with 

 two small pits, and is larger in proportions. In our form this face 

 is considerably roughened. The major portion of the plantar face 

 is represented by the area between the plantar face and the proximal 

 tuberosity on the radial side, and the plantar face proper. It has 



