182 THE MYOLOGY OF THE RAVEN. 



of its arc terminating about opposite the post-pubis of 

 the pelvis. From this origin the fibres of the semiten- 

 dinosus 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 accessort/ semitendinosiis (Fig. 64 bis] is composed 

 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 up- 

 wards to become inserted into the tendinous raphe just 

 alluded to. 



The lower extremity of this tendinous raphe termi- 

 nates, in Geococcyx, in a thin, flat, and delicate tendon, 

 which continues downwards and forwards to the inner 

 surface of the head of the tibia, where it becomes in- 

 serted, the point of insertion being found above that of 

 the semimembranosus muscle, the insertional tendon of 

 which overlaps it. 



The semimembranosus (Fig. 64 bis) in Geococcyx, 

 though thoroughly developed, is rather a slender and 

 thin muscle, markedly so when we compare it with 

 the massive semitendinosiis which overlies it. 



It arises from the outer surface of the ischium, for its 

 posterior two-thirds, on a line situated a few millimetres 

 above the lower free edge of that element of the pelvis. 

 The fibres gradually converge as they pass downwards 

 and forwards, to terminate in a very delicate and thin 

 ribbon-like tendon, which, passing between the broad 

 tibial head of the yastrocnemius and the proximal 



