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Show 1896.] ANATOMY OF PETROGALE XANTHOPUS. 701 ischii and is inserted into the internal tuberosity of the tibia, to the internal lateral ligament of the knee. Meckel says that it is more or less fused with the semitendinosus. The Rectus femoris rises from the ventral border of the ilium and from the posterior Arentral spine by two distinct heads ; there is no origin from the usual place in front of the acetabulum. Macalister found only one head in the Great Kangaroo and Bennett's Wallaby. The Vastus externus is a large muscle and rises from the great trochanter by two heads, which embrace the insertion of the gluteus quartus. The Vastus internus and Crureus are small and normal. The Gracilis comes from the whole length of the symphysis and from the subpubic arch, nearly as far as the tuberosity; it is inserted into the cnemial crest above the semitendinosus. Macalister found it rising from the marsupial bone, a condition which he regards as normal in all Marsupials. The Pecllneus is normal. The Adductor longus is represented by a small muscle, which rises from the outer part of the base of the marsupial bone; it is inserted into the second quarter of the femur and is separated from the rest of the adductor mass by a branch of the obturator nerve. The Adductores magnus et brevis form one large mass wdiich cannot be satisfactorily separated. The femoral artery pierces it, but the part of the muscle which lies superficial to the artery, and which corresponds to the supracondylar slip of many mammals, cannot be separated from the rest. According to Macalister the adductor magnus can easily be separated from the brevis in the Great Kangaroo and Bennett's Wallaby. The Ischio-femoral muscle lies behind the adductors and is quite distinct from them ; it rises from the whole length of the tuberosity and ramus of the ischium, and is inserted by a triaugular tendon into the middle of the back of the femur. It is supplied by the nerve to the hamstrings. The Tibialis anticus comes from the upper quarter of the external surface of the tibia and is inserted into the entocuneiform by a single tendon. In the Great Kangaroo, Macalister found it inserted into the two inner metatarsal bones. The Extensorproprius hallucis rises from the outer tuberosity of the tibia by a small fusiform belly ending in a long tendon, which runs to the inner two of the four toes. This is another instance of the much greater persistence of the extensor tendon of the hallux than of the hallux itself; it is curious, however, that it should have transferred its attachments to the next two toes, and reminds one somewhat of the arrangement of the extensor indicis in the anterior extremity. It should, moreover, be borne in mind that the latter muscle is often one with the extensor secundi inter-nodii pollicis. The Extensor longus digitorum conies from the front of the head and upper third of the fibula, a strong tendon continues this origin |
