PLEISTOCENE MAMMALIA. 



2. Radius, PI. II, figs. 1, 2, 3, 4. 



The general form of this bone is like that of many other carnivora ; the lower half is 

 straight, Avhile the upper is bent gently backwards in a slight curve ; immediately below 

 the proximal epiphysis it is bent sharply forwards, so that the humeral articulation which 

 terminates the bone is set at an angle of about 70° to the axis of the bone (figs. 1, 

 2, 4. a). 



The section of the bone at the distal epiphysis is nearly triangular, with the outer 

 surface convex, while the inner is nearly flat or slightly concave, and the posterior deeply so. 

 This section gradually passes into one which is a flat oval, rather wider on the after edge. 

 The tuberosities (figs. 1, 4, c) give the bone, where they occur, a triangular section, the 

 oval recurring just below the proximal epiphysis. 



The humeral articulation is roughly oval (figs. 1, 2, 4, a), being produced into a blunt 

 point on the anterior edge (figs. 1, 2, e). It is concave with the exception of the anterior 

 edge, where it is vertically convex. There is a slight eminence on the external edge (figs. 

 1, 2, 4,/) which falls gradually away into the concavity of the articulation. 



The proximal ulnar articulation commences just under this eminence (figs. 1, 2, 4,/), 

 and is continued posteriorly round three fourths of the head of the bone to the anterior 

 point (figs. 1, 2, 4, e), where it is deepest. 



The distal ulnar articulation extends nearly the whole width of the bone, and forms a 

 slightly concave oval, wider transversely than vertically, on the upper posterior edge of the 

 distal epiphysis (fig. 3, y, where the edge alone is shown). This is set at an angle of 45° 

 to the axis of the bone. 



The carpal articulation (fig. 3) is roughly trapezoidal in form. The inner or ulnar 

 edge of the articulation is bounded by a semicircular arc, and the surface is concave^ the 

 outer boundary is convex, and the inner is straight when viewed from below, while on 

 the lateral aspect it is boldly curved vertically. The anterior edge of the styloid process 

 is nearly semicircular ; the surface of this part of the articulation is concave vertically, 

 following the under surface of the styloid process, while it is convex transversely. 



The styloid process (/, i, figs. ], 3) is set slightly and obliquely inwards, while the 

 process on the upper anterior edge of the epiphysis is set nearly in the plane of the greatest 

 depth of the bone. 



Some of these bones from the Somerset caves are, as far as considerable fragments 

 allow us to judge, indistinguishable from those of the lion (fig. 4). Others, of which we 

 figure one perfect specimen, arc, as Cuvier remarks, generally far stouter in proportion to 

 their length (figs. 1, 2, 3). 



The only differences in form which we can discover in this or in numerous fragments 

 that we have examined appear to be due to this excess in stoutness alone, and can hardly 

 be regarded as of s{)ecific importance. 



