1896.] ANATOMY OF PETROGALE XANTHOPUS. 701 
ischii and is inserted into the internal tuberosity of the tibia, deep 
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 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 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 Pectineus is normal. 
The Adductor longus is represented by a small muscle, which 
rises from the outer part of the base vf 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 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 Ischio-femoral muscle lies bebind 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 Yibialis 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 mind 
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 
