86 THE ARTISTIC ANATOMY OF ANIMALS 



larger of the two ; the fibula is slender, and situated on the 

 outer side, and a little posterior to, the preceding. The 

 fibula is more or less developed according to the species ; 

 in some it is complete, in others it is very much atrophied. 



This peculiarity may be compared with that which we 

 have drawn attention to regarding the development of the 

 ulna ; but here the seriation is less distinct. Not only in 

 the different species, but even in the individuals of the same 

 species, the development of the fibula presents little regu- 

 larity. In quadrupeds, the bones of the leg are directed 

 obliquely downwards and backwards, so that they form, 

 with the femur, which is directed obliquely downwards 

 and forwards, an angle, the apex of which is placed at the 

 anterior surface of the knee. 



Tibia. — The tibia of quadrupeds is readily comparable 

 with that of man ; as in the case of the latter, its shaft has 

 three surfaces — an external, which is hollowed out in its 

 upper portion, and becomes anterior below ; an internal, 

 slightly convex and subcutaneous ; the posterior, which 

 presents, in its superior part, a crest, the oblique line of the 

 tibia, and some rugosities. The borders separate the 

 surfaces. The anterior border, or crest of the tibia, is 

 prominent in its superior part ; below it gradually dis- 

 appears in passing towards the internal aspect of the 

 inferior extremity. The external and internal borders 

 separate the corresponding surfaces from the posterior one. 



The superior extremity is thick, and expands in forming 

 three tuberosities : two lateral and an anterior. The 

 anterior tuberosity, situated at the superior part of the 

 crest of the tibia, is very prominent ; for this reason the 

 superior extremity is very much expanded in the antero- 

 posterior direction — hence it results that this diameter is 

 equal to the transverse, and sometimes even greater. In 

 man, it is the latter which is the larger. The anterior 

 tuberosity is visible under the skin. 



The inferior extremity, less thick, is prolonged internally 

 by a prominence which corresponds to the internal mal- 

 leolus of man. In animals whose fibula is but slightly 

 developed the tibia presents, on the external part of its 



