570 DR. J. MURIE ON THE ANATOMY OF THE SEA-LION. 
and inferior layers and transverse process for about a couple of inches, and also in part 
springing from the sacro-ischiatic ligament. Folding outwards from its origin, it covers 
the ischiatic vessels and nerves, and glides over the hinder upper edge of the ischial 
tuberosity and origin of adductor magnus. Proceeding thence outwards and down- 
wards, under cover of the biceps and levator ani, and itself lying upon the gastro- 
cnemius, it is inserted by a short broad tendon into the deep fascia above and inwards to 
the fibular malleolus. This fascia is common with that of the biceps and levator ani. 
Action. A powerful flexor of the leg to the tail; and it may be a rotator outwards. 
Levator ani.—Behind the preceding is another broad muscular band reaching from 
the tail to the lower leg, and in close relation with it above the ankle-joint. This 
muscle appears to be homologous with the levator ani, although its insertion differs 
widely from that of the higher Mammalia. The two muscles of opposite sides are 
intimately blended together mesially, and are muscularly fixed to the inferior aspect 
of the tail for the breadth of an inch or more opposite or underneath the fourth or fifth 
caudal vertebra. ‘They run outwards and backwards, and are each inserted firmly by a 
very short tendon into the outer fibular malleolus. 
Relation. Mesially the tail, infracaudal muscles and tendons; the anus; the 
testicles, when these are thrown down into the ischio-rectal fossa; the sacro-peroneus 
muscle as already mentioned. ‘The biceps, the posterior border portion, partly over- 
rides its anterior border. It binds inwards the peronei above the ankle. 
Action. Adductor of lower leg, and rotator outwards of the limb. Besides restrain- 
ing the lower limbs towards each other, the muscles of opposite moieties drag the tail 
from side to side. 
Transversus perinwi.—A sparse layer of fibres is situate in the perineum (7.p), and, 
lying in front of the anus, crosses from the ischio-rectal fossa on the one side to that on 
the other. It helps to render the said fascia tense, and may also assist in pressure 
against the rectum during expulsion of the fieces &c. 
The somewhat triangular-shaped and flat pyriformis (Py, fig. 35) muscle has an origin 
between the ilium and the sacral vertebre in front of the acetabulum for an inch or more ; 
passing outwards and slightly backwards, it is inserted fleshy in the upper and outer side 
of the great trochanter behind the gluteus minimus. It rotates the head of the femur 
forwards and inwards. 
Gemellus superior.—This is not quite so broad as the pyriformis ; it also is pyramidal, 
its broader end arising from the deep surface of the median sacral vertebra, opposite 
the hip-joint. It runs nearly directly outwards (G@.s), and is inserted by a short, strong 
tendon into the summit of the great trochanter. ‘This and the gemellus inferior so 
closely fuse themselves with the tendon of the obturator internus that force has to be 
used in defining the limits of each. 
The gemellus inferior (G.2) is rather the broader of the two; it arises from the edge of 
the ischium, behind the lesser ischiatic notch and for a breadth of above an inch. Directed 
