﻿140 PLEISTOCENE MAMMALIA. 



Hysena, are points by which the first phalanges of those animals may be separated from 

 those of Felis speleea. We know of no others that can be confounded with them. 



§2/3. Second Phalanges. — The second phalanges of all the Feles are characterised 

 by their triangular section, and by the outward projection of their distal articulation ; the 

 latter allows the claw phalange when retracted to fall back outside the axis of the bone, so as 

 to raise the point of the claw over the articulation, and thus protect it from injury. Those 

 of Felis spelaa (PL XXI, 11, 12, 13, 14) closely resemble their homologues of the 

 hind limb, but are longer and more bent externally. The proximal articulation (a), 

 which, following the section of the shaft, is triangular, is composed of two slight concavities 

 divided by a median ridge ; it is deeply excavated on the palmar ridge by a notch and 

 pit, in which is inserted the tendon of the flexor sublimis muscle. On its dorsal edge is 

 a small flattened tuberosity (b), forming the apex of the triangle for the attachment of the 

 tendon of the extensor communis. The bone tapers gradually down to the distal end of 

 the shaft. The distal end is a somewhat rectangular mass, of nearly double the width of 

 the shaft and projecting outwards (d) from the axis of the shaft, and giving the whole bone 

 a curved outline. The articulation closely resembles that on the first phalange of the 

 thumb, which performs similar functions. It affords a means of differentiating the digits 

 of the same paw, that of the second phalange of the second digit forming an obtuse angle 

 with the inner edge of the bone, that belonging to the third a nearly right angle, that 

 belonging to the fourth being slightly acute, while that belonging to the fifth is more 

 acute and very much shorter in its transverse diameter. Like the first phalanges these 

 bones are much longer and more slender than those of the hind paw. 



We have been unable to detect any difference of form between the phalanges of Lion, 

 Tiger, and Felis spelaa. We have met with no British specimens of the third phalanges 

 sufficiently perfect to describe, with the exception of PI. V, fig. 14 : they only differ from 

 each other in size, those of the fore being in the main larger than those of the hind paw. 



§ 2 -y. Measurements. — The following table of measurements shows that the supe- 

 riority of size observable in the other bones of Felis spelcsa as compared with those of Tiger 

 and Lion is carried out in every bone of the fore paw. 



