22 Leach, The Myology of l/ic Bell-Magpie. [,sf7uiy 



crurcBus. The vastus externus arises on the femur at the base of 

 the trochanter, and by fleshy fibres right down the shaft of the 

 bone almost to the condyle. 



The crurcBus is bulky, and arises by a tendon from the anterior 

 aspect of the trochanter, and by fibres down the shaft of the 

 femur. These two muscles and the gluteus primus (94) merge and 

 form the " aponeurotic ligament " already referred to as being 

 spread over the knee, and inserted in the cnemial crest of the 

 tibia. 



The ambiens muscle is absent in the birds under notice, so that 

 these birds are " anomalogonatous," as all Passerine birds are. 



98. The vastus internus [31] is a distinct muscle on the inner 

 side of the leg. It arises on the inner side of the femur just below 

 the head, and is attached down the bone in a straight line, 

 spreading out to be inserted along the inner border of the 

 summit of the tibia just above the insertion of the sartorius (93). 



99. The biceps flexor cruris [29] [32] [^^\ arises broadly by a 

 tendinous fascia from the post-acetabular ridge. It is flat and 

 triangular, and rapidly converges to form a round, cord-like 

 tendon, which passes through a tendinous loop from the lower 

 part of the femur and is inserted into a tuberosity on the back of 

 the fibula, some little distance down that bone. The effectiveness 

 of the muscles is greatly added to by the tendinous loop. The 

 weight is distributed, and a more rapid and more complete 

 inflection of the leg is secured by its means. 



100. The semitendinosus [29], a broad, flat muscle, arises from 

 the hinder part of the post-acetabular ridge and by a thin fascia 

 from the caudal muscles beneath. It passes obliquely down- 

 wards to meet the accessory semitendinosus (loi) at a tendinous 

 raphe which merges behind with the inner head of the gastro- 

 cnemius muscle (109). Strepera and the other birds agree exactly 

 with the American Raven as described by Shufeldt in this muscle, 



loi. The accessory semitendinosus [29] is a flat, board-like 

 muscle arising from the back of the distal end of the femur. It 

 passes directly upward and backward to meet the semitendinosus 

 (100) in the tendinous raphe previously mentioned. 



102. The semimembranosus [30] [36], a long, flat, ribbon-like 

 muscle, arises from the outer surface of the ischium. It passes 

 downward and forward, and becomes a delicate wide tendon that 

 is inserted into the tibial shaft. 



103. The femoro-caudal [30] [59] [61], one of the muscles used 

 in the famous- attempts of Garrod to classify birds by the presence 

 or absence of certain leg muscles, is an interesting muscle, and 

 agrees, in Strepera, with what Shufeldt has described for the 

 American Raven. It arises tendinous from the pygostyle, and 

 passes forward first as a rounded tendon. It becomes a flat 

 muscle, and converges to a flat tendon, to be inserted on the 



