1896.] ANATOMY OF PBTROttALB XANTHOPUS. 701 



ischii and is inserted into the internal tuberosity of the tibia, deep 

 to the internal liiteral ligament of the knee. Meckel says that it 

 is more or less fused with the seraitendinosus. 



The Rectus femoris rises from the ventral border of the ilium and 

 from the posterior ventral 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 exiernus is a large muscle and rises from the great 

 trochanter by two heads, which embrace the insertion of the 

 gluteus quartus. 



The Vastus inlernus and Grureus 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 seraitendinosus. 



Macalister found it rising from the marsupial bone, a condition 

 which he regards as normal in all Marsupials. 



Tlie Peciineus 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 tlie femur and is separated from 

 the rest of the adductor mass by a branch of the obturator nerve. 



The Adductores magnus et hrevis form one large mass which 

 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 IscJiio-femoral muscle lies behind the adductors and is 'quite 

 distinct from them ; it rises from the whole length of the tuber- 

 osity and ramus of the ischium, and is inserted by a triangular 

 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 Extensor proprius 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 raiud 

 that the latter muscle is often one with the extensor secundi inter- 

 nodii pollicis. 



The Extensor longus digitorum comes from the front 'of the head 

 and upper third of the fibula, a strong tendon continues this origin 



