476 DR. R, W. SHUFELDT ON [Nov. 16, 
The patella is found encased in front in this great tendinous sheath 
of the knee-joint, and below the apex of this sesamoid we find the 
enveloped track of the tendon of the ambiens muscles, as it passes 
round in front of the femoro-tibial articulation. The combined 
tendon of the extensor femoris is finally inserted into the cnemial 
crest of the tibial and the lateral boundaries of the summit of that 
bone. Some of the superficial muscles on the outer side of the leg 
are so extended as to take a certain amount of their origin from this 
great tendinous expansion. 
In Plate XLIV. fig. 2 I have very thoroughly divided these two sub- 
divisions of the extensor femoris, in order to show their relative size, 
as well as their relation to each other and the surrounding structures. 
The biceps flexor cruris (Plate XLIV. fig. 1; fig. 2, Bz) arises by 
carneous fibres upon quite an extensive portion of the under surface of 
the over-curled part of the ilium behind the acetabulum, and by along 
tendinous slip which comes off from the free anterior margin of this 
part of the ilium. ‘The fibres converge as they pass downwards, and 
unite to form a somewhat flattened muscle. Opposite the head of the 
tibia, the biceps terminates in a round tendon, of cord-like dimen- 
sions, which passes through a special loop to make its way between 
some of the muscles at the back of the leg, to become inserted on the 
tubercle intended for it on the outer side of the superior moiety of 
the shaft of the fibula. The loop of the diceps (Plate XLV. fig. 1,7) 
is flat and fashioned like a delicate tendinous ribbon. Its upper end 
arises from the side of the shaft of the femur above the external 
condyle, while the lower end comes off from this protuberance just 
below the insertion of the outer slip of the external head of the 
gastrocnemius muscle. A branch of the sciatic nerve also passes 
through this loop in company with the tendon of the biceps. 
The semitendinosus (Plate XLIV. figs. 1, 2, St; Plate XLV. fig. 1, 
St) isa marvellously well-developed muscle in this form, as is also its 
accessory head. Its origin fills about three fourths of the nether 
cavity formed by the posterior overarching portion of the ilium, 
under which it arises. 
Posteriorly, the fibres forming its free margin are so arranged as 
to create a rounded border; the lower end of its are terminating 
about opposite the post-pubis of the pelvis. From this origin the 
fibres of the semitendinosus pass downwards and forwards as a great, 
though somewhat compressed muscle. When within rather more 
than a centimetre’s length of the shaft of the femur, they terminate 
in an oblique tendinous raphe, which latter forms the bounding-line 
between this muscle and the next. 
The accessory semitendinosus (Plate XLV. fig. 1, a.s.¢) is com- 
posed of coarser fibres than the muscle just described. It springs 
from a longitudinal line occupying the distal half of the shaft of 
the femur, and from the upper surface of the hinder aspect of the 
external condyle of that bone. The fibres pass backwards and a 
little upwards to become inserted into the tendinous raphe just 
alluded to. 
The lower extremity of this tendinous raphe terminates, in 
Geococeyx, in a thin, flat, and delicate tendon, which continues down- 
