OCR Text |
Show 1870.] DR. J. MURIE ON SAIGA TARTARICA. 473 or superior limb of the os pubis is stouter than the posterior one. The symphysis, roughened and protuberaut in front, is continued backwards, carinate ; the pubic arch is very deep, narrow, and A-shaped. Each obturator foramen is widely subcircular. The body of the ischium is thin, with a very sharp superior (or posterior) border, its spine forming a wide upward sweep in the bony curvature. The combined tuber ischii (t. ii) and ramus, flattish below and mesially ridged above, have a reverse plane from the body of the ischium; namely, they are horizontal and widely expanded in a trefoil shape. The inner plate or ramus, the thinnest, joins the pubis ; the posterior tuberosity is thick and bulbous; and the third outer spur, which I designate the external tuberosity (e. sp.), has an intermediate thickness and breadth. An angle of 75° approximately gives the separate plane between the iliac and the ischio-symphysial axes. From within outwards the neck of the femur is very broad, but exceedingly short, it and the head being antero-posteriorly flattened. The articular surface of the latter, consequently, is of a transversely oval shape, depressed, and almost at right angles to the axis of the shaft: a roughening indicates the round ligament. The intertrochanteric fossa burrows deeply at the root of the great trochanter, and from that inwards is more open. The great trochanter is large, and posteriorly rises % of an inch higher than the head; its gluteal surface has a long subquadrate outline. Relatively, the trochanter minor is small, and, as in other Ruminants, a third trochanter is wanting. The shaft has a slight forward axial bend ; and a long but feebly developed linea aspera descends its whole length on the postero- outer side. The condyles are large and subequal in size; the intercondyloid space narrow and shallow. With reference to the patella, it is short, stout, and of a nearly equal-sided triangular figure. Its articular surface is but slightly convex. In the fresh condition of the parts the eminence of the outer border is heightened by a wall of cartilage: the prominent ridge thus produced overlaps and grasps the anterior articular rim of the internal condyle, allowing of an upward and downward gliding movement, and preventing luxation from side to side. The articular crown of the tibia is heart-shaped, but with a deep incision for the tibialis-anticus tendon on its outer border towards the front. This causes the outer, fibular moiety or condyle, which superiorly is the more convex of the two, to be shorter than the inner one; whilst it is also the broader, and has a posterior deep-based margin. The tubercles for the crucial ligaments are well developed. The anterior tuberosity is large, though laterally compressed, sharp-edged ; and, from being three-sided and of considerable magnitude above, the shaft narrows and is roundish in its lower two-thirds. The muscular grooves are well marked. Nothing can exceed the compact interlocking, yet easy, gingly-moid movement devised between the distal articulation of the tibia and calcaneum, all chance of lateral dislocation being prevented by the strong internal malleolar plate and the guard of the external side, which is the inferior fibular segment presently to be spoken of. |