1886.] GEOCOCCYX CALIFORNTANUS. 475 



of the muscle, which latter must be cut across and reflected in order to 

 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 the upperside of the ilium itself. 

 The fibres of the roimdish 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.niin) 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 crureeus (Plate XLIV. 

 fig. 2, cr), and the posterior division the vastus externus (Plate XLIV. 

 fig. 2, F.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 iu a broad tendinous 

 expansion, which, as has already been described, is amply reinforced 

 by other insertional portions of the superficial muscles of the thigh. 



