KELLOGG — ^NEW PINNIPED FROM UPPER PLIOCENE 
223 
californicus, though a very rudimentary one is found on that of Eumetopias 
jubata. The coronoid process is broken off. 
The shaft of the ulna is sub-triangular in section. In the area of the greater 
sigmoid cavity the shaft is convex on the external face and deeply concave on 
the internal; the posterior margin of the shaft is twisted towards the internal 
side. The external face of the ulna below the greater sigmoid cavity in both 
Odobenus and Eumetopias is concave. 
The distal end is considerably enlarged in contrast with that of Eumetopias 
jubata. The articular facets are not sharply marked off from the roughened 
shaft. The articular surface on the anterior border for articulation with the 
radius (fig. 4b) is separated from a similar surface for the pisiform by a shallow 
groove. This facet for the radius is slightly convex; it faces forward and slopes 
slightly to the internal margin. The styloid process (fig. 4c) has two articular 
Left Radius of Pliopedia pacifica X No. C. 537, Stanfoed Univeesity 
Santa Margarita, California: fig. 6a, proximal view; fig. 6b, posterior view; 
fig. 6c, internal view. f.c. facet for capitellum of humerus; f.tr. facet for inner 
trochlea of humerus; t. tubercle; u. ulnar facet. 
surfaces, one for the pisiform and the other for the cuneiform, the contact being 
oblique in both cases. Both of these articular surfaces are slightly concave. 
The proximal end of the radius (fig. 6a) is suboval in shape, as in Odobenus 
divergens. The facet for the capitellum is of considerable extent and strongly 
concave; it slopes downward from the ulnar to the anterior margin of the head. 
This facet is continuous internally with the convex articular surface for the 
trochlea of the humerus. The trochlear facet slopes downward to the internal 
margin of the head of the radius. It is also continuous posteriorly with the 
ulnar facet. In general form the head of the radius approaches very closely 
that of Odobenus divergens, the ulnar facet (fig. 6b) being comparatively flat, per- 
mitting of but a limited degree of rotation with the lesser sigmoid cavity of the 
ulna. It differs from both Eumetopias jubata and Zalophus californicus in the 
extent of the facet for the trochlea, which is considerably reduced in these two 
forms. 
The neck is clearly defined on all sides. The tubercle (fig. 6c) is located on the 
postero-internal margin of the shaft, its superior margin terminating 18 mm. 
below the inferior margin of the ulnar facet. Adjacent to it there is a low rugose 
tuberosity. The tubercle is subtriangular in outline; its greater diameter is 
