FELIS SPEL^A. 13 



CHAPTER IV. 



Felis spelaa — Tarsus, PI. IV. 

 Astragalus, fig. 1. 



The astragalus of Felis spelaa is precisely like that of the lion and tiger in form, but, 

 with the exceptions of certain specimens which we shall notice, is much superior in 

 size to those of either of the latter two animals we have met with. 



The tibial or proximal articulation (fig. 1, a, a') is of the usual pulley -like form ; it is 

 inclined to the antero-posterior diameter, at an angle of about 30° ; at the back of this 

 are set the two articulations for the calcaneum, the outer being concave and somewhat 

 broader at the top than the bottom, and this matches the great sigmoid articulation ; 

 the other is subtriangular and matches the small lateral circular articulation [e of fig. 2) 

 of the calcaneum. These three articulations are the surfaces of the head or proximal 

 portion of the bone. 



This is connected with the navicular or distal articulation (fig. 1, b), by a short shaft 

 or neck, as in all the other digitate carnivora. 



This articulation is suboval in form, and bent vertically and diagonally, so that it is 

 highly convex, and matches well the deep concave articulation of the navicular bone. 



The only cave fossil that is likely to be taken for this bone is that of the bear. But 

 the latter is easily distinguished by the extreme shortness of the neck or shaft joining the 

 proximal and distal portions of the bone. The pulley-groove of the tibial articulation is 

 also flatter in the bear, and on the inner posterior edge this articulation is terminated by 

 a sort of spur rising at right angles to the surface, which does not exist in the Eeles. 



Among the many specimens of this bone that have occurred to us there are some in 

 the Taunton collection which are much smaller than the rest, and very little exceed those 

 of a large lion in size. They do not, however, ofier any other difference. 



