206 ZOOTOMY. 



pelvis ; the crus is directed downwards and slightly back- 

 wards, the tarso-metatarsus downwards and slightly forwards, 

 three of the digits are directed forwards and rest with their 

 whole lower surface on the ground, while the remaining toe 

 the hallux or first digit is directed backwards, and 

 slightly raised from the ground at its proximal end. 



in. If the leg is extended outwards at right angles to the 

 body it is seen to present, like the fore-limb, dorsal and 

 vental surfaces and pre-axial and post-axial borders : in the 

 natural position of the parts the pre-axial border is internal 

 throughout the whole limb ; the primitively dorsal surface 

 looks upwards and forwards in the femur, forwards and 

 slightly downwards in the crus, forwards and slightly upwards 

 in the tarso-metatarsus, and upwards in the digits. 



112. The femur, a cylindrical bone consisting of shaft 

 and extremities : the proximal extremity is produced on 

 the pre-axial (inner) side into a rounded elevation or head, 

 the axis of which is at right angles to that of the shaft, and 

 which serves for articulation with the acetabulum: post- 

 axially is a large irregular elevation, the great trochanter, 

 and between it and the head on the actual proximal end of 

 the bone is a facet which works against the anti-trochanter 

 ( 103). The distal end of the femur is pulley-like, and 

 formed of two condyles ; of these the outer or post- 

 axial condyle is deeply grooved in its ventral region, thus 

 furnishing the fibular fossa for the articulation of the 

 fibula ; the rest of the outer and the whole of the inner 

 condyle articulates with the tibio-tarsus. 



113. The tibio-tarsus, a cylindrical bone about half as 

 long again as the femur: its shaft, together with the proximal 

 extremity, corresponds to the tibia ; its distal extremity re- 

 presents the proximal portion of the tarsus, and therefore 

 really belongs to the pes. The proximal extremity bears 



