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Adductor magnus (Pl. XIV. G). - This broad and flat muscle has an extensive origin
(two inches) from the outer edge of the ischium and the obturator fascia; its fibres
slightly diverge as they pass downwards to be inserted into the back part of the lower
half of the femur, and into the upper and back part of the tibia.

Obturator internus. - This arises from the inner side of the opposite margins of the
pubis and ischium, where they form the posterior boundary of the obturator foramen,
and from the corresponding part of the obturator fascia; the fleshy fibres converge in a
slightly penniform manner to the strong round tendon which glides through the notch,
serparated from the rest of the foramen by a short, strong, transverse, unossified ligament,
and is inserted into the posterior part of the base of the trochanter. In its length and size
this muscle resembles the corresponding one in the Ostrich and other Struthious birds.

Gemellus. - This is represented by a single small fleshy strip arising from the margin
of the obturator foramen, close to the emergence of the tendon of the obturator internus,
with which it is joined, and co-inserted into the femur.

Quadratus. - I consider a broad fleshy muscle which arises from the pubis, below the
obturator foramen, and which increases in breadth to be inserted into the femur internal
and posterior to the obturator tendon, to be the true analogue of the quadratus femoris.

Tensor vaginæ and Rectus femoris (Pl. X. H). - The largest and most remarkable of the
muscles which act upon the bones of the leg is that already alluded to as the most su-
perficial of those on the outer side of the thigh. It has a broad, thin, triangular form,
and arises from the spines of the sacryum by a strong but short aponeurosis which soon
becomes fleshy; the carneous fibres converge as they descend*, and pass into a thin apo-
neurosis at the lower third of the thigh: this is closely attached to the musces beneath
(vastus externus and cruræus), then spreads over the outer and anterior part of the knee-
joint, is interted into the patella, and into the anterior process of the head of the tibia.

Owing to the great antero-posterior extent of the origin of this muscle, its anterior
fibres are calculated to act as a flexor, its posterior ones as an extensor of the femur:
all together combine to abduct the thigh and extend the leg, unless when this is in a
state of extreme flexion, when a few of the posterior fibres glide behind the centre of
motion of the knee-joint.

Sartorius (Pl. X XIV. i). - The origin of this muscle is characterized by an unusal
extension, like that of the preceding, with which it is poteriorly continuous: it comes
off aponeurotic, from the anterior and superior margin or labrum of the ilium; the fibres
soon become fleshy, and the muscle diminishes in breadth and increases in thickness as
it descends; it is inserted by short and strong tendinous filaments obliquely into the

* They are not divided into a superficial and deep layer, as in the Ostrich, but form a simple stratum, as in
the Cassowary. Meckel regards the rectus as entirely wanting in the Cassowary, supposing, with Cuvier, the
present muscle to be the analogue of the glutæus maximus and tensor vaginæ united. He say that Professor
Nitzsch observed a like absence of the rectus femoris in the Emeu. Cuvier calls that muscle rectus anticus
femoris, which is described in this monograph as the 'pectineus.'