. Carnegie Institution of Washington publication. PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. extremity of a thin, elongate process directed ventrad and laterad. This surface doubtless corresponds to the outer end of the cartilaginous surface of the proximal end, though separated by a thin, non-cartilaginous interval; and it is very much more protuberant. The trochanter on the tibial side is unusually produced ventrad; its lower border also is situated further down the shaft, and its extremity is smaller. In other respects this femur does not differ from its mate. Tibia (fig. 34 a) .• The
. Carnegie Institution of Washington publication. PERMO-CARBONIFEROUS VERTEBRATES FROM NEW MEXICO. extremity of a thin, elongate process directed ventrad and laterad. This surface doubtless corresponds to the outer end of the cartilaginous surface of the proximal end, though separated by a thin, non-cartilaginous interval; and it is very much more protuberant. The trochanter on the tibial side is unusually produced ventrad; its lower border also is situated further down the shaft, and its extremity is smaller. In other respects this femur does not differ from its mate. Tibia (fig. 34 a) .• The tibia is rather more than four-fifths the length of the femur. It is a rather stout bone, with its upper extremity much expanded. The articular surface for the tibial condyle is elongate and crescentic in shape, separated by a ridge and groove from the rather large surface of an oval shape which articulates with the posterior side of the fibular condyle of the femur. Fibula (fig. 33 f and g) : The fibula is a little longer than the tibia. It has a rather slender shaft, and the lower end is much expanded. The upper end is mod-. FlG. 34.—Ophiacodon minis Marsh, X >2. A, left tibia, dorsal surface; B, right pubis, inner surface; C, right foot, dorsal side: D, right tarsus, ventral side. erately expanded, with a subcrescentic articular surface placed at an angle of about 60 degrees with the plane of the lower end. Its articular surface fits well the elongate, curved articular border of the femoral condyle, sliding, in articulation, forward and inward and backward and outward; that is, in the extended condition of the leg, the plane of the distal extremity is horizontal, while in the much-flexed condition this plane is turned obHquely. The outer border of the bone is nearly straight, the inner border deeply concave to the lower end. The truncate border is gently curved on the inner side for articulation with the astragalus. Foot: The right foot of specimen No. 650 (fig. 34)
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Keywords: ., bookauthorcarnegie, bookcentury1900, bookdecade1910, bookyear1913
