122 PLEISTOCENE MAMMALIA. 



CHAPTER XII. 



Tibia, PI. XIX,figs.l,r,l",2, 2'. Eibula, PI. XIX, figs. 3, 4.' Patella, PI. XIX, figs. 5, 5'. 



CONTENTS. 



§ 1. Tibia. 



a. Description. 

 jS. Measurements. 



7. Definition from other Pleistocene 

 tibiae. 



§ 2. Fibula. 



n. Description. 



/3. Measurements. 

 § 3. Patella. 



a. Description. 



/3. Measurements. 



§ 1. Tibia (PI. XIX, figs. I, 1', 1/' 2, 2').— The tibia? of all the digitigrade Carnivora 

 are remarkably alike in general form, and ofier constant differences characteristic 

 only of genera or widely dissociated species. They present variations of proportion 

 in animals of the same, as great in degree as in the closely allied but distinct species, 

 such as Lion and Tiger, and are therefore of comparatively small value in classifi- 

 cation. We have met with several specimens of this bone in the caverns of Somerset ; 

 the one (figs. 1, 1') is perfect, with the exception of the proximal epiphysis, and belongs to 

 a young animal ; the other (figs. 2, 2') consists of the proximal articulation of an adult ; 

 the former was obtained from Sandford Hill, the latter from Bleadon. 



In the larger Eeles generally the tibia is shorter, both proportionally to the femur 

 and in relation to its own minimum circumference, than in the smaller forms. In Lion, 

 Tiger, and Felis spelaa, it is considerably shorter than the femur ; in the domestic and vrild 

 Cats, considerably longer. The articulations, as we have elsewhere remarked, are 

 frequently larger in Tiger than in Lion, but the variations in this respect are so great that 

 we agree with M. de Blainville in considering them of no specific value. 



§ 1 a. Description. — The tibia of the larger Eeles is a strong bone of slightly double 

 curvature, bent gently forwards distaUy, and backwards proximally, cylindrical distally, 

 but expanding into a prismatic form proximally ; so that the proximal vertical diameter 

 of the shaft is more than double the minimum near the distal end. The prism is so 

 disposed that the narrowest side (fig. 1' b) forms the posterior face of the bone, while the 

 two broader meet in the strong anterior crest (figs. 1, 1' a), which curves gently outwards 

 and may be traced in the adult as far down as the distal end. The head (figs. 2, 2' c, d) 

 of the bone is partially occupied by the two slightly concave semilunar facets for articu- 

 lation with the femur separated from each other by the small bifid eminence termed the 



