OSTEOLOGY AND ARTHROLOGY 93 



than the internal, which on its part is a httle thicker. The 

 trochlea is still more independent of the condyles than in the 

 human femur ; it is separated from these latter by a slight 

 constriction. 



The knee-cap is long and narrow. 



The tibia of the dog is slightly curved from before back- 

 ward : it has the form of an elongated S ; this conformation 

 is in great part due to the very marked projection of the 

 anterior tuberosity and of the superior portion of the crest, 

 which, a little below that tuberosity, turns abruptly back- 

 wards, and thus describes a curve the concavity of which 

 is directed forward. The superior part of the external 

 surface is very much hollowed out. 



The superior extremity is much thicker than the inferior 

 one. It is not only wide in the transverse direction, but is 

 more especially extended from before backwards ; the promi- 

 nence of the anterior tuberosity is the cause of the elongation 

 of this antero-posterior diameter. On the posterior part of 

 the external tuberosity is found a surface to which the 

 superior extremity of the fibula is applied. 



The inferior extremity presents an articular surface, which 

 is formed of two lateral cavities, separated by a crest, which 

 is directed obliquely forwards and outwards. The internal 

 part is prominent, and forms the internal malleolus. 



With regard to the fibula, it is united to the tibia by its 

 extremities and by the inferior half of its shaft. This latter 

 is more expanded below than in its upper part. The 

 superior extremity is flattened from without inwards. The 

 inferior extremity projects beyond the articular surface of the 

 tibia, and forms the external malleolus, which, instead of, as 

 in man, descending further than the tibial malleolus, stops 

 at the same level, and even descends a little less than does 

 the latter. 



In the cat, the curve of the tibia is less pronounced ; this is 

 due to the fact that the crest, instead of being concave in its 

 middle portion, is slightly convex anteriorly. The fibula, less 

 flattened than that of the dog, is united to the tibia by 

 its extremities only, and is separate in the rest of its extent. 



The bones of the tarsus are seven in number, and arranged 



