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Show 1886.] GEOCOCCYX CALIFORNTANUS. 475 of the muscle, which latter must be cut across and reflected in order discover them. From this origin the peroneus longus as a rather thick, concavo-convex muscle passes down in front of the leg, its outer edge dipping down for attachment between the tibialis anticus muscle, which it almost completely covers, and the flexors to its outer side ; its inner edge is free and thin, and overlaps the gastrocnemius. Low down on the outer side of the tibial shaft the fibres of the peroneus longus have converged to terminate in a small narrow tendon. This tendon, just above the condyles of the tibia, bifurcates, the short slip of the bifurcation going to the fascia covering the block of cartilage (which I have termed the tibial cartilage) at the back of the tibio-tarsal joint for attachment, while the longer slip passes across the articulation to the bundle of tendons at the back of the tarso-metatarsus to merge with one of the special flexors. Removing this superficial layer of muscles of the pelvic limb and turning our attention once more to the thigh, the following ones are presented to our view for examination :- The gluteus medius muscle (Plate XLIV. fig. 2, gl.m) is found to be strong and tendinous. It, as in all of the birds that I have examined, fills the concavity of the preacetabular portion of the pelvis, and here in Geococcyx extends laterally much beyond the bone, as this bird has a very narrow pelvis anteriorly, while it demands the use of a powerful set of gluteal muscles. The gluteus medius arises by a strong, flat tendon from the superior surface of the outer moiety of the anterior iliac margin, by a dense fascia from the entire line bounding the preacetabular concavity, and finally by fleshy fibres from tbe upperside of the ilium itself. The fibres of the roundish muscle thus formed converge as they pass to the caput femoris, and, just before arriving at the bone, they terminate in a dense flat tendon, which, passing over a bursa, is inserted at a point on the antero-ext?rnal aspect of the femoral trochanter. The gluteus minimus (Plate XLIV. fig. 2, gl.min) is a very much smaller muscle than the gluteus medius, and is found immediately beneath it to its outer side. In form it is oblong, and fully three times as long as wide. It arises from the outer superior surface of the fore part of the ilium, and passing obliquely downwards and backwards as a flat narrow band of fibres, it becomes inserted by semitendinous ones on the outer aspect of the upper third of the femur, just below the trochanter. This muscle may also ride over a small bursa, just before it arrives at its insertion. The extensor femoris is readily divisible at its lower half into two parts, the bulkier anterior one representing the crurceus (Plate XLIV. fig. 2, cr), and the posterior division the vastus externus (Plate XLIV. fig. 2, V.E). As a whole, this powerful extensor of the leg upon the thigh arises from the antero-external aspect of nearly the entire length of the shaft of the femur, and from a portion of the trochanter at its summit. At about its lower fourth it terminates in a broad tendinous expansion, which, as has already been described, is amply reinforced bv other insertional portions of the superficial muscles of the thigh. |
