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Show 1894.] ANATOMY OF ORNITHORHYNCHUS. 707 tendinosus as a portion of the muscle described above as semimembranosus. MUSCLES OF THE LEG. Gastrocnemius.-Is a large muscle. It arises by two distinct heads: a larger from the upper expanded portion of the head of the fibula; a smaller head arises from the loAver end of the femur. The two portions blend and the tendon is inserted into the os calcis. It does not fuse with the soleus. The femoral head is supplied by the internal popliteal. Soleus.-Arises from the expanded head of the fibula and from the shaft of the same bone. A few fibres arise also from the tibia. The fibres from the fibular shaft arise on the anterior aspect of the bone, and pass backwards between the tibia and fibula to join the other fibres. The two heads blend and pass deeply in a groove beneath the bone supporting the spur on heel. The tendon is here in company with the tibialis posticus. In this situation the soleus divides into tAVO tendons-one passes to the astragalus, the other to the bone supporting the heel. Tibialis posticus passes between the two tendons. Owen states that soleus arises from a large proportion of tibia. This is certainly a mistake; a few fibres only arise from this bone. Flexor longus digitorum.-Is a large strong muscle. It arises from the upper expanded extremity and from the shaft of the fibula. At the ankle it passes between a process of calcaneum and the bone which supports the spur. In the sole it expands and divides into five strong tendons, one for each digit. Coues describes three tendons. Flexor brevis digitorum (perforatus).-This muscle is in two parts. One portion springs from superficial surface of flexor longus and passes to the second and third toes. Another portion arises from the calcaneum and passes to the remaining toes. There is a small flexor accessorius seen on reflecting flexor longus, having the usual relationship of that muscle to the longus tendoD, i. e. passing from calcaneum to deep surface of flexor tendon. The flexor longus is also attached to os calcis by a strong tendinous band. Coues describes the portion arising from flexor longus only as flexor brevis. The part arising from the calcaneum he describes as a dismemberment of flexor fibularis. The two portions have, however, an entirely similar relationship to the longus tendons. I am disposed to regard both the tendinous part and the calcaneal part as dismemberments of the same muscle, i. e. a plantaris, which has contracted separate attachments in its course. The resemblance of the tendinous part to the flexor sublimis (brevis) of the anterior extremity will be at once apparent. Tibialis posticus.-Arises from the upper expanded extremity of the fibula. The tendon passes deeply at the ankle together with the soleus, and, after perforating the latter muscle, very much in the same way that the profundus passes through sublimis in human anatomy, is inserted into a sesamoid bone at junction of the |