The Posterior Limb Skeleton. 105 



the bone,, the latter forming the projecting end of the wing, which is dis- 

 tinguished as the iliac crest (crista iliaca). This portion is considerably 

 thicker than the related dorsal and ventral margins, and also bears on 

 its medial side a somewhat hook-shaped process. Its anteroventral 

 angle is the superior anterior spine (spina anterior superior). The ven- 

 tral margin is slightly longer than the dorsal margin, and is also concave. 

 It is associated with the pubic border of the body of the ilium, and is not 

 connected with the inferior anterior spine. 



The ischium (os ischii) extends backward from the acetabulum, its 

 axis continuing that of the ilium. It consists of a basal portion, or body 

 (corpus oss. ischii) , a superior ramus, and an inferior ramus. The body of 

 the ischium is for the most part cylindrical. It forms the posterior 

 part of the acetabulum, and presents in connection with the latter a 

 deep acetabular notch (incisura acetabuli), which tends to interrupt the 

 articular surface. The acetabular notch leads forward into a depression 

 of the centre of the articular basin, the acetabular fossa (fossa acetabuli). 

 In the natural condition the combined depressions serve for the attach- 

 ment of the round ligament of the head of the femur. The dorsal margin 

 of the bone, belonging in part to the body and in part to the superior 

 ramus, bears a short hook-like projection, the ischial spine, (spina 

 ischiadica). The spine divides this margin into two parts, one of which 

 forms the posterior half of the greater sciatic notch, already described, 

 while the other forms a similar, and, in the rabbit, scarcely less extensive, 

 posterior depression, the lesser sciatic notch (incisura ischiadica minor). 



The superior ramus of the ischium is the continuation backward of 

 the body of the bone. It is a somewhat flattened plate of. bone, the 

 thicker dorsal portion of which terminates in two blunt projections. 

 One of these, the ischial tuberosity (tuber ischiadicum), forms the pos- 

 terior end of the bone, while the other extends in a lateral direction, and 

 is described as the lateral process (processus lateralis). The inferior 

 ramus is that part of the ischium which extends from the superior ramus 

 downward and forward between the obturator foramen and the symphysis 

 to meet the corresponding ramus of the pubis. 



The pubis (os pubis) consists of a basal portion, or body lying imme- 

 diately below the acetabulum, a superior ramus extending from the body 

 to the symphysis, and an inferior ramus extending backward along the 

 symphysis to its junction with the ischium. The anterior margin of 

 the bone, described as the pecten oss. pubis, is thin and sharp. Near 

 the symphysis it bears a minute elevation, the pubic tubercle (tuberculum 

 pubicum), and laterally a more extensive elevation, the iliopectineal 

 eminence (eminentia iliopectinea) . The latter is more conspicuous in 

 older specimens, where it is easily recognizable by its jagged outline. 

 Its lateral margin is continuous with the iliopectineal line. 



THE FEMUR. 



The femur (Fig. 41) is a somewhat S-shaped bone, the body being 

 very slightly arcuate, while of the two extremities, the distal one is 

 bent downward, forming the articulation of the knee, the proximal one, 



