228 Zoological Society. 



superficial or internal side of the semitendinosus . Ins. Into the fascia 

 covering the gastrocnemius and the inside of the tibia. 



Semitendinosus. — This muscle arises from the posterior and outer 

 part of the sacrum and ischium : it is a flattened triangular muscle, 

 which receives the square accessorius muscle from the lower and 

 posterior part of the femur. It gradually diminishes as it descends, 

 and having passed the knee-joint, sends off at right angles a broad 

 and square sheet of aponeurosis, which glides between the two ori- 

 gins of the gastrocnemius internus, and is inserted into the lower part 

 of the angular ridge continued from the inside of the head of the 

 tibia. The terminal tendon, continued from the apex of the muscle, 

 then runs along the outer or fibular margin of the internal head of 

 the gastrocnemius, and becomes confluent with the terminal tendon 

 of that muscle. 



CrurcBus. — This is a simple but strong muscle : it commences at 

 the upper and anterior part of the thigh by two extremities, of which 

 the outer and upper one has its origin extended to the base of the 

 trochanter ; the inner and inferior comes off from the inner side of 

 the femur, beneath the insertion of the glutaus magnus ; the two por- 

 tions blend into one muscle much earlier than in the Ostrich. 



Gracilis. — On the inner side of the cruraus, but more super- 

 ficially, lies a narrow, compressed, long muscle, which rises by two 

 heads, one from the anterior and upper part of the femur, the other 

 from the os pubis ; both soon become blended together and transmit 

 a broad thin tendon to be inserted into the lower and lateral part of 

 the patella with the cruraus. 



Vastus internus. — Two other muscles succeed the preceding, and 

 rise beneath it from the inner and anterior part of the femur ; they 

 have a similar insertion, and obviously represent the vastus internus. 

 The fibres converge to a middle aponeurosis, which increases to a 

 strong short tendon, inserted into the upper and anterior projection 

 of the tibia. 



Popliteus. — This small muscle is brought into view when the super- 

 ficial muscles of the leg which are inserted into the foot are removed. 

 Its carneous fibres extend from the fibula inwards and downwards to 

 the tibia. It' is of relatively smaller extent than in the Cassowary. 



Gastrocnemius. — This consists, as in other birds, of several distinct 

 portions, the chief of which correspond with the external and inter- 

 nal origins of the same muscle in the Mammalia. The gastrocne- 

 mius externus has two strong, narrow, rather flattened tendinous 

 origins, which are attached, one about a line below the other, to the 

 external ridge above the outer condyle of the femur; they are 

 continued into each other about an inch below their bony attach- 

 ments, and thus form a loop or pulley (lined by a synovial sheath) 

 through which the tendon of the biceps glides ; a strong ligament 

 from the outer ridge of the fibula passes backwards to be attached 

 to the confluence of the two tendons. The carneous fibres of the 

 external gastrocnemius come off" from the outer side of the inferior of 

 these tendons, and from the fascia covering the outer surface of the 

 muscles of the leg : they are continued in a somewhat penniform 

 arrangement two- thirds down the leg, upon the inner surface of the 



