362 MR. J. BESWICK PERRIN ON THE 
inseparably blended at their origin, and united also with the rectus. Combined they 
occupy the whole length of the innominate bone. The conjoined muscles end about 
the middle of the thigh in a broad aponeurosis, which joins with that of the vastus 
externus. 
The vasti muscles present a similar arrangement to their analogues in the higher 
animals. The externus is large and well developed. 
The gracilis is a large and triangular-shaped muscle. It arises by a broad fleshy base 
from the posterior margin and surface of the os pubis. It passes downwards, forwards, 
and inwards, terminating in a broad, flat tendon which passes between the outer and 
middle heads of the gastrocnemius, and is inserted into the inner surface of the tibia 
below the head. 
The biceps femoris is a unicipital muscle, of considerable size, situated on the posterior 
aspect of the limb, anterior to the semitendinosus. It arises partly tendinous and partly 
muscular from the ischium, above and behind the acetabulum. It terminates at the 
lower and back part of the thigh in a short and rounded tendon, which passes through 
a loop thrown around it, which acts as a pulley to it. This loop is attached by one 
extremity to the outer surface of the lower end of the femur, just above the origin of the 
middle member of the gastrocnemius, and by its inferior extremity to a tubercle situated 
upon the outer surface of the head of the tibia. It gives origin to a few fibres of the 
outer head of the gastrocnemius. The tendon of the biceps, after passing through this 
loop, is covered by the plantaris, the outer gastrocnemial factor, and two of the super- 
ficial flexor muscles. It is inserted into the posterior surface of the fibula about half 
an inch below the head of that bone. 
Owen states that, by means of this loop, which seems to be common to birds in 
general, the weight of the hinder parts of the body is partially transferred, when the 
leg is bent, to the distal end of the femur; and the biceps is enabled, by the same 
beautiful and simple mechanism, to effect a more rapid and extensive inflection of the 
leg than it otherwise could have produced by the simple contraction of its fibres. 
The semitendinosus arises from the ischial portion of the pelvic bone and its small 
prolonged bony process. It is situated behind the viceps. It is inserted by a broad 
flat tendon into the upper and inner surface of the tibia, immediately below its head. 
The glutei muscles are :—Ist, the maximus vel externus already described; 2nd, the 
medius; 3rd, the minimus; 4th, a small slip of muscle analogous to the gluteus 
quartus. 
The gluteus medius arises from the large concave dorsum of the iliac portion of the 
innominate bone, terminates in a broad flat tendon, which is inserted into the upper 
and external surface of the great trochanter of femur. 
The gluteus minimus is situated immediately below the preceding, and beneath the 
rectus and conjoined tensor and gluteus externus. It arises from the inferior margin of 
the iliac portion of the innominate bone, extending from the acetabulum to the upper 
at 
