206 — ON CERTAIN MUSCLES OF BIRDS. 
posterior superior portion of the semitendinosus. The semitendinosus 
is well developed, and has a broad accessory head. The accessory 
femoro-caudal is peculiar; for, on removing the biceps cruris, its 
superficial portion is seen running obliquely upwards and forwards to 
the whole length of the linea aspera of the femur, from its usual 
Fig. 6. 
Outer view of thigh of Apteryx owenii, dissected. 
s, sartorius ; ¢f, tensor fascie ; b o and b i, biceps, origin and insertion ; gi, I and Iv, 
gluteus primus and-quartus; s¢, semitendinosus; @ s ¢, accessory semiten- 
dinosus ; sm, semimembranosus ; sfc, superficial femoro-caudal ; f c, femoro- 
caudal; a f ¢, accessory femoro-caudal; Ad, adductor. The asterisk on the 
semimembranosus is on the spot at which its second.or true insertion is; the 
other asterisk is placed on the slip of the accessory femoro-caudal (in this case 
specially modified), which is found in Struthious birds and the Tinamous only, _ 
above the sciatic vessel and nerve. 
origin. The sciatic artery and nerve are superficial to this muscle 
(adductor longus of Owen), and parallel to its insertion, as in most 
birds; but they, as is not the case except in the Struthiones and 
Crypturi, perforate it at the sciatic notch, leaving a small portion of 
the muscle (the adductor brevis of Owen) above them. The anterior 
Page 644. terminal fibres of this muscle are situated external or superficial to the 
accessory semitendinosus. 
After this muscle has been removed or turned back, there is seen a 
