﻿PLEISTOCENE MAMMALIA. 



CHAPTER II. 



Felts spelcea — Pore-arm, PL II. 

 1. Ulna, figs. 5, 6, 7, 8, 9. 



We have unfortunately been unable to procure the distal end of this bone. 



The smaller specimens correspond so exactly with those of the lion that we are unable 

 to perceive any difference, save a very slight diminution in size of the recent specimens, 

 which, we believe, have been all, or nearly all prepared from animals which have lived 

 most of their lives in cages. 



The larger, however, present some differences, which, we think, necessary to describe. 



The line drawn from the proximal end of the humeral articulation to the summit of 

 the olecranon forms a more acute angle with the axis of the bone in F. spelcea than in F. 

 leo (figs. 5, 6, 7, 8, 9, a, b). 



The large humeral articulation (figs. 5, 6, 7, 8, 9, a, a') is precisely alike in both. 



The proximal radial articulation (c, c', figs. 5, 6, 8, 9) is more nearly at a right angle 

 with the axis of the bone in F. spelcea than in F. leo, though it still forms an angle of 60°, 

 that in F. leo being 50°. In F. spelcea the articulation is shallowest posteriorly, in F. leo 

 anteriorly. 



The coronoidprocesscisstronglydeveloped,butnot more so proportionally thaninthe lion. 



The shaft of the bone appears, from the largest fragments we have met with, to have 

 been straighter and deeper, in proportion to the thickness in the larger, than the smaller form. 



But the most marked difference to the eye is shown by the comparison of figs. 6 and 

 9, which show the extremes of the variation (fig. 8 being a somewhat intermediate form). 

 It will be seen that in fig. 6 a strong ridge runs parallel to the back of the bone on the 

 outer or radial surface (figs. 6, 8, 9, d, d), forming a broad shallow groove which extends 

 downwards as far as the specimens we have seen allow us to observe. It will be seen 

 that this ridge terminates or dies away in fig. 9 a little beloAV the radial articulation (fig . 

 9, d) ; in the recent specimens of the lion it is still less visible. 



As, however, the length and prominence of the ridge appears to vary precisely as the 

 size of the specimens, and we have examined above twenty, we cannot look upon 

 it as a characteristic difference. Generally speaking, the surface of the bone in the 

 larger specimens appear to present well-defined riclges with rounded contours, and smooth 



