112 



wards, bounding the concavity which extends along the outer third of the anterior 

 surface of the shaft of the femur *. The ridge which defines the inner boundary 

 of that concavity commences at the upper, anterior and internal angle of the 

 great trochanter, and running vertically down the shaft of the bone, gradually 

 subsides towards the end of the middle third. Two shorter ridges, equidistant 

 at their origin from each other and from the preceding, run in parallel lines 

 downwards and a little inwards, along the midspace of the anterior surface of 

 the femur, between the great and small trochanters : they likewise bound shallow 

 depressions, the seats of attachment of muscular masses subservient to the move- 

 ments of the leg. The small trochanter is a vertically oval, depressed tuberosity, 

 situate directly upon the inner border of the femur, two inches below the head, 

 from which it is separated by a smooth and shallow concavity. The posterior 

 intertrochanterian space is smooth and convex, except where it sinks into the 

 cavity which partly undermines the posterior columnar prominence of the great 

 trochanter. A narrow rugged tract is continued from the lower part of the small 

 trochanter, obliquely downwards upon the posterior surface of the shaft, near the 

 middle of which it expands, then terminates. The surface of the femur,at the middle 

 of the anterior part of the shaft, is marked by the same slight reticulate risings 

 which characterize many other parts of the skeleton, affording attachment to 

 muscular fibres. A vascular groove leads obUquely from the long vertical ridge 

 to the rising above the inner rotular articular surface, but the rest of the anterior 

 surface of the femur is pretty smooth. The posterior surface of the distal half of the 

 femur offers a more rugged and irregular character : many ridges at the middle 

 and outer part of the back of the bone descend, converging, to a rough elevation 

 forming the outer boundary of a wide and somewhat shallow depression on the 

 outer half, and just below the middle of the back part of the shaft of the femur. 

 This depression is smooth, as is also the surface adjoining the condyles. The 

 orifice of the canal of the medullary artery, which is of disproportionally small 

 size, is situated at the back part of the femur, a little above the middle in one, 

 rather below it in the other bone ; in both the canal is directed downwards : its 

 small size relates to the absence of a medullary cavity in the femur of the Mylo- 

 don. The outer border of the shaft terminates by forming a projecting angle 

 above the outer condyle. The upper part of the outer boundary of the femur is 



• Plate XVII. 



