FELIS SPELAVA. 125 
§ ly. Definition from other Pleistocene tibie.—The tibia may be distinguished 
from all other bones associated with it in Pleistocene deposits, by the following points :— 
From any of the Deer or Ox tribe, by the oblique direction of the astragaline facets ; from 
the Horse, by the slenderness of the shaft. It approaches that of the Hyzena very closely, 
but in the latter animal the crest is longer, both proximally and distally, so that the head 
is flatter and the whole shaft more decidedly prismatic. Its size, also, would at once 
stamp its character. In the Bear the shaft is decidedly prismatic throughout, the distal 
articulation is much wider, and the astragaline depressions shallower. The internal 
malleolus does not descend so far, while the whole epiphysis extends much further 
externally. The crest also is much smaller, as well as the patellar tubercle; the extero- 
anterior tuberosity is much lower, and the depression for the adipose ligament does not 
cut off the internal facet from the patellar tubercle, but passes down straight over the 
latter; the semilunar facets are flatter, and the posterior attachments for the muscles are 
far more distinctly marked. 
We know of no figures of any fossil tibize of Felis spelea. 
§ 2. Fibula (Pl. XIX, figs. 3, 4).—We have met with fragments only of the fibula 
of Felis spelea, one of which consists of the shaft, and the other of a perfect 
distal end; both were obtained from Bleadon Cave, and are figured in Pl. XIX, 
figs. 3, 4. 
§ 2a. Description—As we have never met with the proximal end of the bone that 
afforded origin to the soleus muscle, we omit all notice of it; analogy would show that it 
was identical in form with that of the living Lion. The shaft of the bone (fig. 3) at the 
proximal end is triangular in section, and its posterior surface is shown in the figure (a). 
The roughened surface affords point of origin to the peroneeus longus. The shorter of 
the remaining two sides or the anterior is the fibular origin of tibialis posticus, which is 
attached to this bone in Felis. Below, the shaft becomes cylindrical, having a sharp high 
ridge (4) on the internal surface, which is the line of attachment for the fibulo-tibial inter- 
osseous membrane. On the posterior side of this ridge, about the middle of the bone, is 
the origin of the flexor longus pollicis, and lower down that of the flexor longus digitorum. 
It curves forward near the distal end and forms a sharp wedge-like tubercle, on the outer 
side of which (fig. 3, e) is the origin of the peronzeus tertius. At the immer angle of the 
distal end there is a roughened surface, which is developed in the adult into a second 
sharp ridge, that also runs spirally backwards half round the bone, so as to form the 
posterior distal edge. On the outer side of this, a little below the middle, is the origin 
of the peronzeus brevis (fig. 8, d). The two ridges above described are opposite to each 
other at the distal end, and form a flat blade-like expansion, on the inner side of which is 
a slight polished elevation, which is the distal articulation with the tibia. 
The extensor communis digitorum or cnemodactylus of Riolan is not attached to the 
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